In 1782 the New River Company approached Boulton & Watt with a view to commissioning a new engine to stand alongside Smeaton’s. Matthew Boulton and James Watt had been manufacturing vastly more efficient steam engines since 1775, and in 1782 Watt patented doubleacting and rotative engines. Designs for a machine incorporating these latest refinements were prepared, but this was not built, though a similar engine was erected at Chelsea Waterworks. Agreement for the New River Head engine was not finally reached until February 1785, when Boulton & Watt undertook to supply a double-acting engine with a 32 in. cylinder and 8 ft stroke, working by parallel rather than rotative motion. This was at work by the end of 1786, in Mylne’s westward extension of the engine-house. Buttresses were again included, to reduce vibration, and survive on the building’s west side. The new pump chamber, again to the north, also housed a staircase and a high-level cistern. The Boulton & Watt engine was about three times as efficient as Smeaton’s, which had been deemed wholly useless by 1792. (fn. 47)

Redundancy, technological advance and ever-increasing demand provided scope for further improvement. In 1793 Robert Mylne gained approval for the acquisition of a second engine which, working only occasionally, would double the quantity of water raised. There was no urgency, Mylne explaining to Boulton that ‘I have begun this business rather early, on purpose to have full time for thought, afterthoughts and Pentimento’s’. (fn. 48) Accordingly, work on this improvement appears to have continued into 1797. It involved replacement of the Smeaton engine and further extension of the engine house, this time on the east side, for the installation of a double-acting parallel-motion engine with a 36 in. cylinder, 8 ft stroke and wooden beam. In 1794–5 Mylne recast and unified the engine-house as the D-plan barrel-like building that survives, giving it symmetry from the north with quadrant or curved walls. As in his reworking of the Water House, Mylne devised a characteristically neat solution to the extension of an already extended building, combining tidy regularity with a touch of grace. Smeaton’s core at the centre was refitted with a high-level cistern in its north chamber and a staircase in its south chamber, lit from the south by a new opening, subsequently blocked. Two chimneys rose in the south wall of the engine house extensions. The much lower boiler-house to the south was also given symmetrically curved walls, but during the installation of a boiler in 1796–7 it was found to be too small, and a lean-to boilerhouse evidently had to be added to the east. (fn. 49)

The replacement of the New River Company’s pipes in cast iron in the second decade of the nineteenth century was accompanied by further upgrading of the pumping machinery, W. C. Mylne overseeing the installation of more powerful Boulton & Watt engines. The western engine of 1785–6 was replaced in 1811–12 and the eastern engine of 1794–6 in 1816–18, in both cases with singleacting parallel-motion engines with 48 in. cylinders, 8 ft strokes and cast-iron beams. The staircase and north wall of 1785–6 were removed, and the boiler-houses were again enlarged for double boilers. (fn. 50) These improvements were completed in 1818 with the removal of the staircase of 1794–6 so that Smeaton’s south chamber could be reused as a single chimney for both engines. Mylne replaced his father’s two stubby chimneystacks with a single tapering shaft rising 110 ft from the ground (Ills 222, 223). It was an apt moment for the raising of such a monumental structure, which dominated the Clerkenwell skyline until its demolition in 1954. Not only had the New River Company brought to completion the modernization of its water-distribution system and seen off the challenge of rival suppliers, but it was poised to begin the most ambitious town-planning and building programme yet seen throughout the entire district.

224. New River Head, looking west in 2005. Engine house to rear, coal stores to right, public garden to front

Mylne oversaw another round of engine house improvements in the 1840s, following the successful introduction by Thomas Wicksteed of a Cornish engine for the East London Waterworks at Old Ford in 1838, and inventions enabling the compounding of old engines to work with high-pressure steam on the Cornish system. Accordingly, the Boulton & Watt engines at New River Head were altered to work expansively with new cylindrical boilers, each to provide 150 hp, one in 1845–7, the other in 1848–9. Associated work, for which George Mansfield & Son were the builders, included the introduction of cast-iron windows, the rebuilding in much enlarged form of both boiler-houses, incorporating some earlier brickwork to the south, and several additions: a north-east porch, a staircase tower to the west, and a seven-bay coal-store wing to the east.

All this survives relatively unaltered (Ills 221, 222, 224). The boiler-houses and the coal-store wing each have similar hipped roofs with light wrought-iron trusses like those patented in France by Camille Polonceau in 1837. The elegant and ingeniously constructed cast-iron staircase of 1848–9 was supplied by Henry and Martin De La Garde Grissell of Regent’s Canal Ironworks. These younger brothers of Thomas Grissell, the great contractor, were leading manufacturers of structural ironwork from c. 1841. Inside the engine house, other remnants from this phase include some substantial cast-iron girders, pocketed to carry the ends of floor beams in the west engine house, and of I-section in the north chamber of Smeaton’s building, to support cisterns or condensation tanks for preventing steam loss, under a tall iron cylinder on an octagonal brick base behind the chimney. A third small engine of 25 hp that appears to have been introduced in the early 1850s may have stood below this assembly. (fn. 51)

Later in the nineteenth century a long low workshop range was built in phases along the site perimeter north of the engine house. The engines were again replaced in 1897–8 and 1901–3, with triple expansion machines of 65 hp by James Simpson & Co. of London, and 120 hp by Yates & Thom Ltd of Blackburn. At this time some windows were renewed, using fixed wrought-iron frames, and the outer bays of the engine house appear to have been reroofed, the iron cylinder giving way to a lantern. Steam power was replaced by electricity in 1950. With the engines removed, a concrete floor was inserted c. 1957, the engine house (now minus its chimney) having been refused the protection of listed-building status. This was gained in 1972, preventing demolition, and scuppering a plan to build new offices. The building has stood little used since, the east boiler-house having served as a garage and then to house generators, with alterations in 1983–5. Since 2003 the south boiler-house has held two Siemens pumps that in serving the London Ring Main have renewed the building’s working link with the Claremont Square reservoir. (fn. 52)

225. Metropolitan Water Board Offices, ground-floor plan as built. To left, Oak Room on first floor and (inset) its original orientation on first floor of Water House in 1693. H. Austen Hall, architect, 1914–20

Former Metropolitan Water Board Offices

The large block of flats that has taken the name ‘New River Head’ and the address No. 173 Rosebery Avenue was built in 1915–20 as the central offices of the Metropolitan Water Board, replacing the Water House and displacing the Round Pond. It was in 1913, a decade after its formation, that the board decided to build its headquarters at New River Head. The proposal came from Frederick Lionel Dove, who represented the London County Council on the board. Islington-born, he was the chairman of Dove Brothers Ltd, the eminent Islington builders, who had undertaken several contracts for the New River Company. His suggestion split the board. The General Purposes Committee found little beyond ‘historical associations’ in favour of siting the headquarters outside the ‘zone within which an important public body would normally erect their offices’—that is, in or adjoining Westminster. Despite this, and higher costs than those of a more central site, the vote went in favour of Dove’s proposal, seemingly a victory for sentiment over rationality. The inherited site, however, pro vided scope for large premises, and it was intended that any remaining land would be sold for development. This goes some way towards explaining the resultant building’s orientation: there was to have been a new street along its west side. (fn. 53)

Early in 1914 six invited architects prepared schemes, the brief including incorporation of the Oak Room from the Water House into the new building. The plans were assessed by E. Guy Dawber, who favoured Herbert Austen Hall over his competitors Brown and Barrow, T. Edwin Cooper, Herbert O. Ellis, Edwin T. Hall, and Henry T. Hare. (fn. 54) H. A. Hall had an appropriate track record as an architect of town halls, and his plans were praised by Dawber for being compact and well laid out, ‘each department being kept distinct and self-contained’. (fn. 55)

Building began in July 1915 with T. W. Heath & Son as contractors, but they proved too slow and were soon replaced by Rice & Son of Stockwell. War brought work to a halt between June 1916 and January 1919, and inflation pushed up building costs. Despite economies, these rose from the £85,000 (fn. 56) originally projected to £298,417 when the offices opened in May 1920.

The complex comprises a quadrangle with the main entrance on the short Hardwick Street front, and a triangle with one side aligned to Rosebery Avenue (Ill. 225). Hall’s original scheme was of Beaux-Arts character, the main façades to have been faced in rusticated stone. But by 1915, to reduce costs, he had substituted a more English neo-Georgian idiom, to be built largely in red brick over a rusticated stone lower storey. The new building rose just three storeys, with attics to the eastern ranges (Ills 226, 230).

In 1933–6 a further attic storey was added to the eastern ranges, with two attics to match on the western and northern ranges. Although provided for in Hall’s original scheme these do seem to detract from the building’s proportions. The Portland-stone tower at the eastern angle (Ill. 176) was added at the same time, as was a dining-room for board members on the top floor at the north-east corner of the main quadrangle, its cantilevered bowwindow ends offering views across London. Rice & Son were again the builders. (fn. 57)

Internally, design was less compromised by economy. There are several spaces in which Hall adeptly explored the classical architectural vocabulary (Ills 227, 228). A narrow stone-lined entrance lobby has friezes bearing the seals of the water companies merged to form the Metropolitan Water Board, all set over appropriately watery Vitruvian-scroll mouldings. This leads to the spacious entrance hall that gives access to one of the two main staircases, which have bronzed handrails and scrolled ironwork balustrades, as well as to the former Rental Ledger Hall, occupying the whole court within the main quadrangle, and top-lit through an elliptically arched ceiling. On the first floor, the former Board Room in the south range was fitted out with a dais and concentric benches, like a town-hall council chamber, its Ionic columns and pilasters being a variant of the Bassae order that had become fashionable in Edwardian London, most prominently at County Hall, built in 1909–22.

Former Metropolitan Water Board Offices and Oak Room

226. Metropolitan Water Board Offices, perspective of south front in 1915

227. Board Room on first floor, c. 1921

228. Rental Ledger (latterly Revenue) Hall, from south in 1937

229 (opposite). Oak Room chimneypiece

230. Former Metropolitan Water Board Offices, from Rosebery Avenue in 2006

231. Ceiling painting of William III by Henry Cooke

232. Detail of Oak Room ceiling

Conversion of the offices into 129 flats was carried out in 1995–8 by Broadway Malyan, architects, for Berkeley Manhattan, a consortium made up of Berkeley Homes (Kent) Ltd, the Manhattan Loft Corporation and Kennet Properties, a subsidiary of Thames Water. Glass conservatories were added on the roof, and the Rental Ledger Hall, renamed the Revenue Hall, was opened up as an enormous communal lobby. The Board Room, made into a single voluminous flat, was redecorated for David Dorrell to Minimalist designs by McDowell and Benedetti. (fn. 58)

The Oak Room

The transplantation of John Grene’s Oak Room of c. 1693 from the demolished Water House into the new headquarters of the Metropolitan Water Board was an early and remarkable instance of the preservation of an historic interior in such a context. The room had not been an incidental acquisition. On the contrary, the board had purchased it separately from the New River Company in 1904, for £2,000, in order to prevent it being dismantled and removed. There was thus a commitment to retaining the Oak Room long before there were plans for a new building at New River Head. (fn. 59) This may have been at least partly due to Charles FitzRoy Doll, an original and actively engaged board member, who was also an architect with antiquarian interests (see the Devil’s Conduit, below). ‘Wrenaissance’ taste had long appreciated the room’s quality, a watercolour view by John Crowther having been exhibited at the Royal Academy in 1888.

Removal of the woodwork, together with the ceiling and some later fireplaces, was entrusted to Laurence Turner. He was able to move the ceiling in a single piece, a feat which may have been made easier because it had been taken down in 1868 and secured to new ceiling beams. (fn. 60)

The installation of the Oak Room on the first floor of the new offices involved not only its re-orientation but the loss of the panoramic views it had previously offered. Windows could be provided on one side only, looking west towards the engine-house. Some alteration to the ceiling and re-organization of the panelling was involved, but apart from that the room survives unmutilated (Ills 225, 229, 232). The decorative scheme is of the highest quality. On the fully panelled walls are richly carved upper or frieze panels and an overmantel with the arms of William III framed by naturalistic ornament on fishing and hunting themes. The carving has, inevitably, been attributed to Grinling Gibbons. However, as Gibbons’s material of choice was lime-wood, it is more likely that this is the work of another virtuoso carver, like Jonathan Maine, who did work in the more intractable oak. (fn. 61) The enriched plaster ceiling bears the arms of Sir Hugh Myddelton and Grene along with numerous relief panels depicting a variety of water subjects, ranging from angling, boats and a swan, to dolphins, a mermaid and Neptune. Again the identity of the craftsman is not known. Within lush frames, gilded since at least the 1860s, there is a large central oval oil painting by Henry Cooke, depicting William III allegorically upheld, perhaps by Virtues (Ill. 231). (fn. 62)

Another room contains the ceiling from the east loggia of the Water House, bearing the New River Company’s Old Testament motto ‘et plui super unam ciuitatem’ (‘and I caused it to rain upon one city’), (fn. 63) and the date 1693. (fn. 64)

During the Second World War the panelling was removed by Maple & Co. for safekeeping, but it was now impossible to remove the ceiling without cutting it up. The central painting, restored in 1922, had to be restored again following its reinstatement in 1945. (fn. 65)

Former Water-Testing Laboratory

The Laboratory Building at No. 177 Rosebery Avenue, on the east side of New River Head, was built for the Metropolitan Water Board in 1936–8 for water testing. The board’s laboratory staff of seventy had responsibility for monitoring biological, bacteriological, chemical and chlorination aspects of London’s water. This was done in a strikingly suave building designed by John Murray Easton, of Stanley Hall & Easton and Robertson, a firm beginning to specialise in medical and scientific buildings. The builders were Walter Lawrence & Son Ltd.

233. Water-Testing Laboratory in 1938. John Murray Easton, architect, 1936–8

234. Former Water-Testing Laboratory in 2005

235. Former laboratory staircase in 1990

Broadly functional, the building was fully attuned to architectural fashion, the clean Modernist lines being ideally suited to its hygienic purpose. On a steel frame, the elevations are of brown-red Himley brick, with stone dressings and steel windows (Ills 233–6). Like the board’s offices, the Laboratory Building faces away from Rosebery Avenue, the entrance front here addressing Arlington Way. The curved main range is sited away from the road to minimise vibration, its longest convex elevation facing north to maximise the even light from this aspect for the individual laboratories, concentrated on this side; the presence of a basement reflects the site’s former use as a filter bed. The strong contrast between the monumental verticality of the eastern entrance block and the sweeping horizontal lines of the main range has been reduced by the forward extension of the latter’s upper storey in 1963–4.

For the semi-circular south end of the entrance block John Skeaping sculpted the Metropolitan Water Board arms in Portland stone, incorporating the New River Company motto. Below, tall glass-brick windows light a circular cantilevered staircase of great panache (Ill. 235). Over the staircase is a blue plaster ceiling with a gilt incised figure of Aquarius the water-carrier, designed by F. P. Morton. (fn. 66) The building was converted to make 35 flats in 1997–8 by St James Homes, the joint venture that Thames Water formed with Berkeley Homes, Geoff Beardsley & Partners acting as architects. (fn. 67)

236. Water-Testing Laboratory, ground-floor plan as built

The Devil’s Conduit

Standing just north of the former Metropolitan Water Board offices, and within the revetment wall of the Round Pond, is a re-sited medieval conduit head, a small, stone, bunker-like structure known as the Devil’s Conduit (Ill. 214). This was moved to New River Head in 1927, having previously stood north-west of Queen Square in Bloomsbury. Comprising upper and lower chambers, the latter barrel-vaulted and ashlar-lined, it was constructed in the fourteenth century as the conduit head or tank at the upper end of the pipes that supplied water to the Greyfriars monastery (later Christ’s Hospital) on Newgate Street. In 1893 Philip Norman discovered the long disused structure behind a house and proceeded to research and publish its history. During demolition work for an extension to the Imperial Hotel, Russell Square, in 1911–13, the conduit head was rescued by Charles FitzRoy Doll, the hotel’s architect. Doll had sat on the Metropolitan Water Board since its inception, when he had been Mayor of Holborn, as he was again in 1912–13, and was accordingly well placed to arrange for the relic’s re-erection at New River Head. (fn. 68)

Boundary Wall, Myddelton Passage

The eastern length of purple-grey stock-brick boundary wall on the south side of Myddelton Passage, running from Arlington Way to the west, is the last surviving section of New River Head’s late Georgian perimeter security wall. It was built in 1806–7 to replace a high timber fence, and completed the enclosure of the site by brick walls. (fn. 69) The western parts have been rebuilt in yellow brick, perhaps in 1935, (fn. 70) and there have been smaller yellow-brick repairs. Some of the original brickwork bears a quantity of carved graffiti of mid-nineteenth to early twentieth century date, discussed on page 216.