In reply to tony:
Thanks - wasn't so convinced by the ones with inbuilt briefs but those look interesting - the 2 others also look exactly what I was after... annoyingly the local run4 it doesn't have them in - web presence far bigger than retail presence I guess.
May just have to order and return if fit isn't right - I've tried a few on but have found that even if legs and waistband are tight fitting, the crotch isn't necessarily so.
Appreciate the links - have largely lost will to live trawling e-sites and looking through 150 pairs of shorts one by one trying to find ones without rear pocket....