Aha! my BT1100 Bulldog has bones 10mm longer than standard which, I am told, equates to a difference of 30mm in seat height. ( I just didn't know for sure if irt was up or down ) I think that is why, despite my increased decrepitude, I can get on and off it and hold it up when stationary, far better than my 2003 version.
Thanks very much for info.