BD2000, I kinda did a 80%+ run this evening during Jog Scotland run see below, I know what you mean about the HR monitor once or twice mine has given me very strange readings.
Keir, it really only takes a few minutes to do once you know what you're doing, good treadie run earlier, I struggle on them 
Spen that's some serious mileage,
Brian, do these faster runs I do a couple of times a week have any impact on the 75% stuff
NN, which P&D plan are you following, I downloaded the book on my kindle last month and I was thinking of following the 55 mile on when I start training for Loch Ness in May.
Santa, your run today sounded awesome, I really enjoy getting out into the countryside as well, fortunately it is not difficult up here in Inverness 
Tonights run was a non Hadd run with a 4 miles easy then 4 mile tempo with a hill thrown in for good measure. stats for the run below
I enjoyed running in the snow tonight, but I did notice it requires a little more effort.