Well done Becs, that is an excellent time and it sounds like you ran the race well, evenly and barely able to walk when you finished, which probably means you gave it just the right amount. Well done and enjoy the recovery.
CR - Sorry to hear about your bad luck with the sickness and your right to not try running after that. Enjoy the fell season though and Great Langdale marathon. I did Snowdonia a few years back and did like the big climbs to break up the running pace and exercise a few differet muscles.
I agree that off-road improvement doesn't neccesarily relate to on-road, but I think the longer distances have certainly helped me improve overall. Combined with a speed session every week or two its given me stamina and endurance to keep my pace longer. Which has really helped at 3m to HM distance on road the last year or so. Marathon is a different beast to half and below though.
I'm back into trails now, Calderdale Hike at the weekend was a nice 38m with plenty of on-route food (sandwiches, biscuits, bananas, sweets, hot and cold drinks), a good variety of underffot conditions and climbs. All in all I never pushed too hard, kept eating and just got around. Feel a lot less achey afterwards than post-marathon too. I'm going to stick to my practiced discipline for awhile now I think.
But ,I will be doing a few more fell races as hills on most trail won't cut it for TDS training, so maybe see you out there CR - unfortunately the lakes are too much petrol burning away for me to get to regularly though. Easy weekend coming up, but after that the weekends are booked up: Woldsman 50 (trail), Pendle Cloughs (fell), a couple of days running peak district, Bob Graham Round pacing (maybe). Will try and get over to do a lakes long or super-long some time this summer too (unfinished business at wasdale). Will be fun.
Good luck all, conditions look perfect for you in London this weekend, not much wind, cool, and maybe some rain to cool you further. So don't worry about the weather, just stick to your pacing plan and try not to get impatient if it feels too easy in opening miles (like I did). If it still feels easy at 13m then its your day 