Thanks to RSR member Tom WIlson for the loan of this extractor. Tom made this extractor himself and has allowed me to publish pictures and dimensions for other to see.
When I come to replace my faulty oil seal I shall take pictures and post them.
Typical of TW's shipbuilder heritage - I am sure this is better than teh extractor Rover finally devised for the P5 halfshafts - this would be too long for tyeh P2 ones