The developer has signed up Mace to convert the 101m high Portland House office building into 206 luxury apartments above ground floor shopping.

It is the biggest of several new office conversion schemes planned by Land Secs in the capital.

The developer also plans to convert a 1960’s Oxford Street building into 89 apartments above reconfigured prime retail accommodation.

The redevelopment of Portland House forms part of the wider planned regeneration of Victoria by Land Secs.

It currently plans to invest £1.7bn in the west London area developing 2m sq ft during the next decade.

The latest office-to-flats scheme, which has been designed by architect Sir David Chipperfield, is also linked to the delivery of 63 affordable homes at nearby Castle Lane, for which planning consent has already been granted.

Colette O’Shea, head of development for the London Portfolio, said: “By completely remodelling the building, we will provide a residential building of exceptional design and quality which will include facilities for its residents.

“This is the latest and largest of our residential development projects, which will have a hugely beneficial impact on the whole of Victoria.”