Predict my marathon time...

I'd say around 3:35 ish.

Incidentally, I think you could benefit from some longer distances at aerobic pace. Even your 'easier' runs average 155BPM. Perhaps a few longer runs at 145BPM pace would do you some good.

3:19:51.5

Done another two 20 mile runs since posting, both in around 3 hours.

Despite feeling fairly strong (managed a 7:24 last mile!) I experienced some cramp in my right calf on the first of these runs and cramp in my left calf on the one I've just done.

Both came in at around 17/18 miles and wasn't enough to really slow me down and it eased off somewhat at the end but a bit worried that it will really kick in at 22/23.

Any tips on how to avoid cramps on race day?

I've recently heard if you lose a lot of salt when sweating, it a big factor in causing cramps... maybe something to look into.   My brother does Ironman and got cramps a lot until they did this test where they extract some sweat somehow and look at the salt in that amount, it was very high; since then he has increased his salt intake he doesn't get cramps...

Who was closest?

I meant to comment on this again!

I ran it in 3:47.

After 13 miles I was running at sub 8:00 minute mile pace but then almost every subsequent mile was slower than the last!

Great experience, and for my first marathon, not a bad effort! Have certainly learnt a lot.

Freemers closest

TimR wrote (see)

I'll play. 3h40m.

WIth the very first prediction I make it that TimR was closest, but what do I know with my dodgy comprehensive education and dumbed down maths A level 

Right.

Colin McLaughlin wrote (see)

Freemers closest

Yay!

Chimpster wrote (see)

TimR wrote (see)

I'll play. 3h40m.

WIth the very first prediction I make it that TimR was closest, but what do I know with my dodgy comprehensive education and dumbed down maths A level 

Bugger!

Leicesterfan - well done on your first marathon...are you going to do another one? (if so more long runs will be the key!)