The former exhibition block of Watson House, now the Piper Building, and the attached relief panels by John Piper

The Piper Building, originally the exhibition block of Watson House (formerly the headquarters of the North Thames Gas Board and research laboratories of the Gas Council), dates from 1957-1959 and was designed by E R Collister & Associates. It was later converted in 1997-8 by Nelsonville Ltd, with Lifschutz Davidson as architects, and now serves as an entrance foyer and commercial units within a mixed residential and commercial development. The building is square in plan, flat-roofed, and two storeys high, built on pilotis with an external staircase to the south. The ground floor is enclosed by glazed screen walls, containing the main entrance, and a canopy, added during the conversion, projects over the gated pedestrian access. The first floor is supported by pilotis with an undercroft beneath, and the first-floor elevations are blind, displaying a band of 29 relief panels around the three exposed faces. Notably, the interior of the building is not considered to be of special architectural or historic interest for listing purposes, though any alterations that might affect the building’s character still require Listed Building Consent.

The building's exterior is concrete framed with rendered elevations, and the glazed screens are held within steel frames.

The defining feature of the building is the series of 29 relief panels by the artist John Piper, created between 1961 and 1962 and fabricated by Gillespie and Manzaroli Associates. These panels, made of polyester resin reinforced with glass fibre (GRP), are fixed to the first-floor level of the three external walls. The south elevation has six full-size panels and two smaller panels near the fire-escape stair. The east elevation features eight full-size panels flanked by a pair of narrower panels, with L-shaped panels at the corners. The north elevation displays six full-size panels and three narrower panels towards the adjoining six-storey block. The full-size panels measure approximately 365cm (12ft) by 275cm (9ft). The panels utilize abstract imagery, comprising spiral, ovoid, and rectangular motifs in shallow relief against a pale background of speckles and horizontal striations. The palette shifts from a near-monochrome effect to a tonally richer appearance towards the front and centre, employing ochres, oranges, browns, and black against backgrounds of mid- and light blues and greys.