Inglis Badrashi Loddo (IBLA) has converted a Grade II-listed Edwardian civic building in London’s Harrow on the Hill Conservation Area into five apartments.

Occupying a prominent position on the village green at the southern end of the High Street, the building was completed in 1913 as public offices for Harrow on the Hill Urban District Council. It was designed by Harry Prince, a pupil of Arts & Crafts architect E. S. Prior, following a competition for the commission. The building served as council chambers for most of the 20th century before being converted into offices and a caretaker’s flat in the 1960s. Later alterations in the 1980s infilled the original central lightwell with toilets, a staircase, and additional accommodation, obscuring the original plan.

Built on a sloping site near Harrow School, the building rises over three levels with two frontages. The ground-floor elevation opens onto the High Street, while a basement looks onto Byron Hill Road. It stands between the old Harrow Fire Station and the former branch of London County Bank, both dating from the 1880s.

Adapting the historic building

IBLA’s longstanding clients, a private development company, acquired the building in 2013, around the same time as the neighbouring fire station. Following the rejection of previous applications, the clients approached IBLA in 2020 for its experience in the refurbishment and adaptive reuse of historic urban properties. The architects secured listed building and planning consent for five flats in 2021.

The brief balanced three ambitions: maximising the land value, creating functional and atmospheric homes, and respecting the building’s listed status. Much of the fabric had suffered from unsympathetic changes during its previous use, including the infilling of the courtyard, the insertion of heavy steel structure, and services running directly through historic cornicing.

IBLA’s design centred on two main interventions: reinstating the original lightwell and introducing a new timber-clad spiral staircase within the courtyard, reorganising the building’s vertical circulation. The architects began with a detailed analysis of the existing fabric, alongside a close study of historic photographs and original drawings. Removing poor-quality, late 20th-century additions allowed the original lightwell at the heart of the building to be reopened, bringing daylight back into the building while restoring the original plan form.

As IBLA director Kim Loddo explains: ‘The challenge wasn't simply converting an old office building into apartments — it was understanding how the building originally worked and allowing that logic to shape the new design. Restoring the courtyard gave the building back its centre, while the new spiral stair and freestanding service pods allowed us to create five contemporary homes with minimal intervention to the historic fabric.’

Reworking the circulation

Reusing the original grand staircase to serve all the new flats would have consumed too much of the frontage and left the smaller units isolated from it. Instead, the architects treated the entire main frontage as a single duplex, entered from the High Street.

A new timber-clad spiral staircase in the reinstated courtyard provides independent access to the rear units from Byron Hill Road: Flats 1 and 2 on the lower-ground floor, Flat 3 on the upper-ground floor, and Flat 4 on the first floor. Each flat has its own bedroom, washroom, living space, and fully equipped kitchen.

In Flat 90, the principal duplex, the original timber panelling was sanded, re-oiled, and fire-protected, and the existing doors were retained. Marble light fittings and picture-rail-mounted spotlights avoid fixing into the panelling or ornate ceiling roses, while kitchen servicing is threaded through the existing fabric. The main staircase and hallway were restored by lifting glued-down carpet, removing later fire doors, and reopening blocked windows.

Flats 1 and 2 are self-contained in the basement, while Flat 3 is a two-bedroom apartment. Flat 4 occupies a former meeting room, retaining original oak parquet flooring and cornicing. Its layout also includes a Jack and Jill toilet shared between two bedrooms, which doubles as a secondary fire escape route for one of the rooms.

Freestanding service pods

Across the flats, new servicing and amenity elements are introduced as freestanding timber-clad ‘pods’, scaled and detailed like furniture rather than partitions. Containing showers, toilets, basins, and storage, they are designed to sit below the level of the original picture rails and cornicing.

Internally, they are finished in a water-resistant timber laminate, with blue-grey herringbone tiling echoing the pine parquet found throughout the building. Taps and ironmongery have a brushed brass finish, referencing the original knob furniture, which was retained wherever possible.

A new stair within the courtyard

The spiral staircase is engineered to carry its own enclosing walls. The lifting anchors cast into each precast concrete tread are used as fixing points for the curved timber structure above.

Loads pass down through the central column to a small new pad foundation, avoiding the need to break out the existing 300-millimetre concrete slab. This allows the whole extension to be built above ground with minimal excavation.

The staircase is clad in thermally treated pine, with narrow, offset boards secret-fixed to follow its curve, creating a weathered counterpoint to the masonry outside and the timber pods within.

John Helyer, consultant at Price & Myers, explains: ‘Price & Myers provided the structural engineering design for the project, which included removing previous infill to reinstate the open courtyard and construct the new circular stair core. The precast concrete stair treads are wrapped in a timber-clad studwork wall, which relies on the stairs for stability, requiring early subcontractor design input.’

Repairing the building fabric

Elsewhere, non-original openings were removed and the facades restored to their original composition of red brick, stone quoining, and a clay-tiled roof with a copper-domed cupola. Walls and floors were insulated where possible, secondary glazing was added for warmth and security, and new services were routed carefully through the fabric to protect the original details.

The project reflects IBLA’s broader approach to working with inherited urban fabric. At Harrow on the Hill, a series of targeted alterations allows the listed building to accommodate a new residential use while retaining and restoring significant elements of its original fabric.