Applegarth is the chief executive of troubled building society Northern Rock which he joined in 1983 as a graduate trainee.  

Quickly rising through the ranks, he was appointed head of planning in 1989, assistant general manager in 1992, executive director in 1996 and finally chief executive in 2001.

John White, Chairman of Persimmon said: "In his time on the Board, Adam has made a significant contribution to the company, for which we are very grateful.

Nevertheless, we understand his desire to focus fully on the issues at Northern Rock PLC, and we wish him well for the future."