 Alan donated large sums to a number of religious houses, but most famously founded, with King William II, the Benedictine St Mary's Abbey in York in early 1088.Alan was among the first four magnates to support William II of England against the Rebellion of 1088 in favour of the Duke of Normandy, Robert Curthose.The uprising was led by the recently freed Odo, Earl of Kent, Bishop of Bayeux, and joined by several major magnates.