Marks & Spencer has announced that three of its non-executive directors are retiring from the board on July 11, the date of the annual general meeting. They are Sir Michael Perry, 67, Sir Ralph Robbins, 68, and Sir David Sieff, 62, a previous executive director of M&S. Sir Michael Perry was appointed to the board in 1996 and is chairman of Centrica plc, Shakespeare Globe Trust and the British Government's Senior Salaries Review Body.