From what I remember of 'Billy' he could stand up for himself and would probably relish someone knocking on his door asking!!!!
The Birketts are actually an outdoor activist dynasty cos Bill's dad Jim Birkett was a top lakeland pioneer, did the first ever XS in the Lakes, and Bills nephew is Dave Birkett modern hot shot rock climber.
All three of em have made great contributions to the outdoors and are well documented on t'internet, loads of dave birkett stuff on Youtube.