Kelvin House, 15 And 17 Marshall's Lane And Cart Walk

Kelvin House, located at 15 and 17 Marshall's Lane and Cart Walk, is a three-storey office building designed by James Steel Maitland between 1937 and 1939, with a later addition in 1949 that incorporates mid-19th century elements. The building has a rectangular plan and features an Art Deco front elevation, along with a 1949 first-floor bridge link to a truncated section of a two-storey former industrial building from the 19th century. It is constructed of rendered brick with sandstone and concrete dressings.

The principal elevation faces east towards the River Cart and includes a central two-leaf timber door set within a broad architrave that rises from a deep sandstone base course. This door features a prominent drop-keystone and a corniced canopy that forms a shallow balcony above a window. The outer bays of the ground and first floors have horizontal lights, while the upper floor has a horizontal row of six lights linked by a bracketed concrete sill. The roof parapet has a deep overhanging concrete cope that rises in two steps towards the centre and is topped with a flagpole.

To the left of the main building is a link structure with a shallow segmental arch at the ground level, featuring two-leaf iron gates leading to a car park. The first floor has a gently bowed window with horizontal glazing supported by plain brackets. Adjacent to this is a mid-19th century piend-roofed building that is angled to the left and has segmental-arched windows on three elevations. The rear of the building has regular fenestration.

The windows throughout the building are predominantly small-pane metal-framed, with hopper openings in the upper sections. The roof is covered with grey slate.