My first go tonight... finally I can add something to this thread!!
It was out to a roundabout and back, with a [surprisingly large!] hill in the middle with a brisk headwind for the first half.
It was all a bit of a blur but I realised my goose was well and truely cooked about 10 minutes in when I was struggling to maintain double figures towards the top of the hill, I think I worked much too hard into the headwind going uphill. From then onwards it was a balancing act, watching my heart rate and trying to keep it in a sensible range (I hit 196, average was 188. My maximum is 197).
time? - total 29.50 by my watch, after I got to the turn in 16.20 so the second half was 13.30. Pleased with the second half, but I think if I'd taken 5% off the work in the first part, then I'd have a lot more left towards the end.
I was waiting at the start and chatting to a couple of others and this guy I vaguely recognise rolls up. "Evening Hutch", someone says, then I twigged where I'd seen his photo. He came past at about 10 minutes, having started 3 minutes behind, which was nice.