In reply to Captain Fastrousers: To answer a few points. It was fantastic fun for the 70km I held on, it felt a lot like racing in a bunch and was the toughest 2 hours I can ever remember.
I was chatting to the club fellas and explaining that I was new to the sportive thing and was it ok if I hung on and tried to do my turn when I could, to which they were ok. I'm not sure my mate was talking to them or not, and if he asked permission to be there.
Perhaps his finish up the last hill does show that he had more in the bank than he was letting on - I have always accused him of this - riding to his heart rate monitor rather than to what he feels is his maximum. I'm sure when I went up to the front if I had a heart rate monitor I would have broken it! But then his strategy got him to the end still strong rather than crawling like me, so I can't really criticise him!
A sportive is a timed organised ride, where people start in waves and get a time at the end. For some, a team timetrial, for others a nice day out.