The pictures show what was once one of London’s most heavily guarded buildings transformed into a glamorous destination for visitors.

They have been released by property company Qatari Diar to mark the announcement of the name of the Grosvenor Square hotel, which will be known as The Chancery Rosewood.

The Grade II-listed landmark was designed by Finnish architect Eero Saarinen. It was also the first purpose-built embassy in London when it was completed in 1960.

Its conversion into a five-star hotel — part of a broader overhaul of Grosvenor Square — is being overseen by architect Sir David Chipperfield.

The 137 rooms are being designed by Joseph Dirand. It will also have an Asaya spa, five restaurants and a large ballroom.

David Chipperfield Architects said they aimed to restore Saarinen’s original vision of creating a “palace on the park”.

Mr Dirand said: “It was originally conceived as a fortress and inspired by the Doge’s Palace in Venice.

“It will now become the new British palace of hospitality and lifestyle.”