Carl and dave, thanks for your thoughts on pacing.
Well done on the 20 milers everyone, very good in these conditions... I set out to run 20 this afternoon and ran in snow/sludge most of the way - I only managed 12.5 before cramping up. Got 14 done in the end but concerning given I was going 15 secs slower than last wk (9'35 pace this wk).
All I can think is that I must have been slightly dehydrated (didn't drink enough Saturday) AND the difficulty of running in snow took more out of me than I thought it would. Really pleasant horizontal sleet most of the way as well - nice!