cheers for more succinct response suggestions guys. I think I would have scared said skinny teenager to death or appeared to be some kind of weirdo (or moreso than is true) had I stopped and started explaining my reasoning 
BN - Must admit I rarely check cut-offs as usually only have an issue in fell races. Trail events usually seem less harsh and I only find myself checking if I blow it big time! As ultra-trail events go I guess its quite tight, 3hr for first 9m, 6hr for 21m, 7hr for 26m, 10hr for 41m, 13:30 for 52m. Seems odd that after 3mph allowance for first 9m - I know some people start steady, but... - that the stakes are then upped so that you have to have moved at 4.1mph for first 10 hours. And the third cut off seems to make the second cut-off redundant, it was originally 7:30, but at 7hr the 1 extra hour for further 5m from cut-off 2 is odd. I'm not worried myself unless I have an off day as form has been good, but I know there are usually a fair few people behind you and me in trail events we do Nick and they have it tough.