Helly - thanks for the response. I am not sure I appreciated the "lovely last quarter" at Greensands - thanks to my poor pacing, I took longer descending Leith Hill in the last quarter than I did climbing it in the first quarter; and the final climb over the Nower almost finished me off.
From what you say it doesn't sound as though Three Forts is appreciably harder (apart from the extra mile), so I think I'll aim for the same sort of time, and see how it goes.
Can anyone offer a comparison between this and the Greensands Marathon? I did the Greensands last October, in just over 4:30. It was great fun, but thanks to the 70 minute cut-off to get up Leith Hill, I set off too fast, and ended up with a massive positive split of 2:00 for the first half, and 2:30 for the second half. My Garmin recorded climb/descent of a bit over 3,000 feet for Greensands, so on paper the races look pretty similar.
I would be interested in anyone's thoughts on how the two compare, so that I can try and pace this one better.
Chimney - thanks - the banter was much appreciated.
BRM, it would be interesting to know how many others (as I did) ran the 6.5 miles up to Leith Hill faster than the 6.5 miles down. My 6.5 mile splits were roughly: 56 mins, 65 mins, 82 mins, 70 mins - a positive split of over 30 mins (2:01/2:32). Whilst I was pleased to do it in 4:33, it does suggest that better pacing (maybe a minute a mile slower in the first quarter) would have led to a faster overall time.