Well, I did it, much to my surprise.  The first eight miles were all fine and I was on for sub-two hours (comfortably), then I discovered the hideous trick the organisers had played on us all - mile nine was all uphill.  It wasn't too steep, but it just ...didn't ....stop.  I gave up aiming for sub-two hours after that and just focused on finishing, which I did in 2:02:43.  I'm told that's not too bad for a first attempt!

I had a quick look to review who beat me and was pleased to see that the oldest person to finish before me was only 68.  He only just beat me though, crossing the line about one-and-a-haf miles ahead of me!

Thanks to all of you for your support!

Nick