The Grade I listed building, in St Martin’s Place, just off Trafalgar Square, is getting its biggest ever makeover since the National Portrait Gallery took it over in 1896.
The project, called Inspiring People, includes construction of a new entrance and forecourt as well as a reconfiguration of the galleries, designed by Jamie Fobert Architects and heritage consultant Purcell. There will also be more retail and catering space and a new Learning Centre.
Work is due to complete in 2023.
National Portrait Gallery chief operating officer Ros Lawler said: “The renewed building will allow us to be more welcoming, engaging and accessible to all, with new and refurbished galleries for exhibitions and the permanent collection and better quality learning facilities.”
Gilbert-Ash managing director Ray Hutchinson said: “The redevelopment, which is in line with our track record of taking on projects which require innovation to succeed, presents a great opportunity for Gilbert-Ash to further cement our profile in delivering outstanding landmark buildings of international significance.
“We look forward to working closely together, and indeed imaginatively, with the National Portrait Gallery, the architects and the other disciplines and our trusted supply chain to deliver this prestigious project.”