Hall McKnight repairs the hidden heart of King's College London

There’s a lovely moment in the new engineering department at King’s College London, when you stand in the immaculate concrete shell of a high-spec workshop and look up though a glass roof to see the creamy stonework of an elaborate Georgian facade rising five storeys above. To one side, its giant rusticated base sits just beyond the windows. On the other, glazed walls reveal an equally striking juxtaposition as a scarred screen of ancient brickwork slices through a coolly clinical laboratory. It’s through such careful layering – of old and new, of materials, spaces and views – that architect Hall McKnight has produced a remarkably practical yet characterful interior in the semi-subterranean Quad Building, set below a grand quadrangle at the heart of the grade I-listed campus.

Four buildings enclose the long courtyard. The east wing of the 18th-century Somerset House, designed by William Chambers, was absorbed by the college in 2010. It faces Robert Smirke’s slightly later King’s Building, the university’s original home. At the southern end there’s another bit of Somerset House, facing out to the Thames. And to the north, on the Strand, a brutalist building added in 1972. The 3,000m² Quad Building, extending under the entire courtyard, was built in the 1950s and occupies the space between two bits of made ground: the courtyard at the level of the Strand, and the Thames embankment 9m below. Windows look into a deep, narrow lightwell on the west side that extends into a crooked passage leading to the riverside.

In 2015, Belfast-based Hall McKnight won consent for an ambitious plan to improve connections between the disparate pieces of the campus, centred on a glass-roofed ‘learning commons’ under the quad. But following protests at the proposed replacement of some historic buildings on the Strand, the project was dropped. At the same time, King’s agreed a lease on Aldwych Quarter, the grand arc of 1920s buildings across the Strand, shifting its centre of gravity northward. 

So when the practice was asked to look again at the Quad Building there was less scope for radical surgery. Instead, the brief was to work within the disused, semi-derelict structure to make a departmental base where students could move freely between flexible teaching rooms and workshops, and which could be easily adapted to other uses in the future. 

It also included a much-needed facelift for the courtyard itself, a dreary expanse of black asphalt. With the clay hollowpot deck unable to bear much weight, however, and a need to maintain level access with the Strand, the architect had to settle for a layer of resin-bonded gravel. ‘We struggled with that,’ says practice partner Ian McKnight. ‘It’s the last material most architects would choose for a landscape between two listed buildings.’

To add some distinction the surface is inlaid with a grid of metal strips, whose proportions echo the facade of the King’s Building. Its off-centre layout hints at the axis of a symmetrical courtyard originally intended by Chambers, who planned another wing on the site of Smirke’s building. The reference might be lost on the average passer-by, but the effect is well judged: sufficiently odd to have presence, but not enough to unsettle the wider composition. And the gravel, in two well-chosen shades of beige, harmonises with the surrounding facades, giving a new coherence to the whole ensemble. 

As this surface is the most prominent ‘elevation’ of the Quad Building, Hall McKnight was keen to give some expression to what lies beneath. A circular concrete bench sitting in the middle of the court turns out to be the top of an oculus over a new staircase. A double helix inscribed around the base is a nice touch: it was here that Rosalind Franklin captured the first images of DNA molecules. Similar structures cap four lightwells behind the stone balustrades of the King’s Building.   

These modest protrusions give a rough sense of an efficient plan that has replaced a warren of cellular rooms and lightless corridors: on each floor there are two big teaching spaces with adjacent workshops in new structurally independent buildings set within the former lightwells, and some circulation space in the middle. ‘The concept is simple,’ says McKnight. ‘Complexity came from the interactions between the different levels and the neighbouring buildings, and with the layers of history’.

The way in is via the main entrance to the King’s Building, and downstairs to its basement. Previously, the route then led on to low doors at either end of a long corridor, but Hall McKnight spotted the potential for a more impressive – and conveniently central – threshold in a dusty archive below the entrance hall. It doubles as an informal study area open to all students. Brick vaults have been limewashed, stiffened with steel lintels and panelled at low level with crisply detailed timber and sage-green fabric to conceal services. With Jean Prouvé-designed wall lights and vaguely mid-century furniture, it’s elegant but comfortable. 

New openings in the 1m-thick walls lead to the Quad Building, and another small ‘learning commons’ – this time with a woodblock floor and an implied frame of chunky oak columns and beams, like a building within a building. Students might make a connection with the sumptuous Gilbert Scott-designed chapel on the upper floors of the King’s Building. ‘It is a bit of a conceit,’ says McKnight, ‘but in the various spaces shared with the whole university we wanted to make something of its time, with a level of detail and texture that relates to architecture made in a different age.’

With no external walls, daylight is borrowed from an adjacent teaching space, through windows set into a partition that encases existing columns and incorporates storage and display shelves for students’ work. Its evident thickness is of a piece with the weighty construction of the King’s Building. 

There’s another echo of Georgian in the grandeur of a helical concrete stair set in an oak-lined hall below the oculus. It has a beautifully plastic quality, but the choice of material also reflects the practical challenges of construction. The only access was via the narrow passage to the embankment, and concrete could be pumped from outside. 

The stair descends to the lower basement, where switchback ramps deal neatly with level changes across the site. It forms part of a route through the Quad Building accessible to all students – a lingering vestige of Hall McKnight’s original scheme – so views into the open-plan 120-seat labs on either side give the engineering department a visible presence in the campus.

These are more utilitarian, with a monochrome palette of pale grey resin floors and white-painted columns with a bump-resistent skirting of black MDF. Ceilings are laden with foil-wrapped ductwork – which caused some headaches in the design process, says Hall McKnight associate Emma Smart, as the building had to be insulated internally, and the roof is too fragile to take fixings. 

Rows of custom-made light fittings spanning the width of the room were a significant but worthwhile expense. Their large surface area allows light intensity to be kept low. With adjustments throughout the day, that creates a convincing – if false – sense of abundant daylight. 

The elegant simplicity of new fixtures and finishes is counterpointed by a string of brick arches that stand between the labs from the workshops – the last surviving piece of an 19th century structure that once stood on the site of the Quad Building, which supports the balustrade of the King’s Building above. The glass walls of the compact ‘maker spaces’ are set slightly back from this charismatic relic, enhancing the impression of depth and volume in a confined space, like theatrical flats. 

It’s those subtle but significant details that define Hall McKnight’s approach here. Present throughout, they reflect an ambition to enhance the campus in a way that goes far beyond what was necessary simply to equip the Quad Building for use, improve energy performance or get listed building consent. Despite few opportunities for bold statements, this diligent, sensitive renovation has made a building that lives up to its extraordinary setting.

IN NUMBERS

Gross internal floor area 3,280m²
Construction cost including external deck £28.1m 
Construction cost including external deck £5,325/m²
Months on site 23