thanks for the offer but it was the main casing that split on the lower mounting due to the frame bending. I think I will be able to get it welded but I need to make sure the mainshaft is not bent as the rear wheel also went out of alignment causing both chains to lock up under undue tension.
Everyone in the club including yourself have been great with offers of assistance and Bruce Longman has helped with square 4 spares for the engine. Sooner or later this old bike will be back in circulation, and later today I even started it myself (with my good leg) so continued British biking is still a real possibility.
Knud - the last time I saw his van it was parked on its roof on the motorway pointing the wrong way -so hopefully it is written off