At some point in the past, from talking to folks from the Leisure Owners Association it seems the mast foot and step were replaced or modified.
Originally, I believe the foot and step should both have been aluminium, with the step having a single upright running bow to stern central to the plate, and the foot having a central slot which fitted over this upright.
On our boat however the step has two uprights running bow to stern on either edge of the plate, and the foot is in fact fashioned from a wooden block.