Dixon Jones Architects have replaced Allies and Morrison on the controversial scheme to convert the Regent Palace Hotel on London's Regents Street into a modern office development.
To date any proposals for the site has faced major opposition from several conservation groups, who one a significant victory last May when they got the Edwardian building listed.
It is understood that Allies and Morrison had voluntarily stepped down from the project, telling the developer, Crown Estate, that the office had taken the scheme as far as it could.
A row broke out in early 2004 between conservation groups and Crown Estate over whether the building should be saved.
The Twentieth Century Society and SAVE Britain's Heritage lobbied both the government and English Heritage over the importance of the 1915 building and its Art Deco bar and restaurant, which were both by Oliver Bernard.
The Allies and Morrison faced a major setback when the DCMS decided to register it as Grade II-listed.by Ed Dorrell