Many thanks for that information bmacm.I recall Canon's Gate caponier being in a bit of a dodgy state too. I believe there is a covered shaft in the ditch close to C.T. which has a tunnel connected to a shaft on the other side of Constable's Bastion. I found this shaft as the wooden cover had rotted away and fallen down the shaft. A couple of Forum lads had a look years later but earth down the shaft had blocked access.