Mutual friend & clubmate, Ken, was the lead on the latest restoration project until his retirement. It was cheaply built, the imposing stone facing being thin tiles over a chert rubble structure.A monument to waterproof footwear, I think.
The town had no connection with the Duke apart from the name, but, after Waterloo, decided they should commemorate his victory. He then became prime minister and hugely unpopular, so construction halted. He died, and was thus popular again, so they then finished it.
Pete Luxton told of club runs to a coffee stop there and a climb to the top for the view.