An expert study contradicted TfL’s conclusion that the Art Deco masterpiece at 55 Broadway, over St James Park Tube station, is “no longer fit for purpose”.

Last summer TfL launched a competition for designs to replace Charles Holden’s 1929 landmark, London’s tallest office block at the time. It led to architects TateHindle being appointed to plan a residential apartment scheme which could net TfL more than £120 million.

But a study by conservation specialists Richard Griffiths Architects, commissioned by TfL itself, said the building, dubbed “London’s first skyscraper”, could be modernised to provide “good offices”, according to Architects’ Journal magazine. Heritage groups have called on TfL to rethink, but it said the redevelopment has to be “a commercial success”.