Major office retrofit approved by City of London

The project, designed by architecture practice Orms for developer Ho Bee Land, will transform the historic office building into a sustainable, high-performance workspace while preserving and reinterpreting its architectural legacy.

Located just north of St Paul’s Cathedral and adjacent to Postman’s Park, 1 St Martin's Le Grand occupies a prominent island plot. Originally constructed in 1895 by Sir Henry Tanner for the General Post Office, the building was extensively altered in the 1980s when it was redeveloped by Nomura. That phase retained only the Portland stone façade and structural steel frame, making the current retrofit more adaptable.

The Orms-led design approach aims to respect the building’s layered history while improving spatial efficiency and environmental performance. Working within protected sightlines to St Paul’s and the historically sensitive surroundings, the architects have planned a retrofit that retains the building’s embodied carbon and introduces extensions to achieve a new gross internal area of around 300,000 sq ft.

One of the project's key sustainability milestones is its selection as a pilot scheme for the UK’s forthcoming Net Zero Carbon Buildings Standard, announced in 2024. The refurbishment will act as a benchmark for environmentally responsible office retrofits in the Square Mile, aligning with evolving commercial sector commitments to reduce carbon emissions and meet national climate targets.

The retrofit includes the removal of inefficient 1980s French-style mansard roofs, replacing them with set-back three-storey corner pavilions and attic storeys that soften the massing. The uppermost levels, 11 and 12, will adopt a modernist character while remaining largely hidden from street level, maintaining visual harmony with the building’s historic facade.

Internally, the design addresses longstanding inefficiencies. Three existing cores will be consolidated into a single, centralised core, enabling more flexible and open floorplates. The main entrance will be relocated to St Martin’s Le Grand, providing access to a new double-height reception that visually connects to Postman’s Park and creates a more coherent internal flow.

Detailed architectural studies of Tanner’s original design informed the update. The team mapped each elevation to understand historical changes and used this analysis to restore symmetry, particularly along the St Martin’s Le Grand frontage. The main entrance will be repositioned at the centre of the elevation, beneath a new archway that mirrors the building’s northern end.

The scheme reflects a growing trend in the City for intelligent retrofits that prioritise reuse, sustainability, and heritage sensitivity. With approval from the City of London now secured, the project moves forward into the detailed design phase.