Armitt will first become a senior independent director before taking over as deputy chairman at the next annual general meeting.
Berkeley chairman Tony Pidgley revealed the move as he unveiled another sparkling set of half-year pretax profits, up two thirds to top £101m once again.
Turnover rose 20% to £405m as the house building business pushed ahead with several landmark housing projects.
Pidgley said Berkeley was bringing three large scale urban regeneration schemes in London to the market – Riverlight in Battersea, One Tower Bridge and Kew Bridge.
He said the speed with which these sites would be developed would be driven by the strength of market demand.
In the first half, Berkeley acquired 1,271 plots on eight sites.
In London, this included a commercial property in EC1 which has a planning consent for 700 homes, 46 homes on Albert Embankment and One Blackfriars, which has an established consent for a 52 storey development.
The other five sites are residential housing schemes which have been acquired in locations outside Greater London and across the South East.
In most cases, these sites were acquired with a planning consent or have been acquired conditional upon a planning consent being obtained.
Berkeley obtained planning consents on 14 schemes in the first half totalling in excess of 2,000 plots.
Notably, these included consents for 744 new homes at Fulham Reach and 249 new homes at Carnwath Road, Fulham.
Berkeley is currently developing four student schemes for delivery over the next two years, all of which have planning. These include schemes for Oxford Brookes University, the University of Kent, Imperial College and the University of the Arts in London.
Pidgley said: “The Localism Agenda and the Government’s Plan for Growth represent the most significant changes to the housing industry for a generation.
“When implemented effectively, I believe Localism will achieve housing and economic growth at the same time as ensuring powerful local engagement, decision making and benefits for local communities.
But he warned: “The challenge for Government policy at both national and local level is to reduce the burden of unnecessary red tape, regulation and bureaucracy which acts as a barrier to more housing by slowing delivery, in some cases by more than a year, following a resolution to grant planning.
“Without addressing this issue, I fear planning on a large scale will become the sole preserve of the strongest and most financially secure developers which will be detrimental to the desire to increase supply and competition to stimulate economic growth.”
