With a clear head and having talked to people on here and at the plumber's merchants I now have a better idea of what happened. I have sat in the bathroom and examined the situation. What I discovered was that the two pipe ends poking out of the floor were different heights. The one which blew off last night is bent just under the floorboards and so has no play upwards and sits 15mm below the other one. The rad was fitted to the wall based on the height of the taller pipe end. The shorter one was then under constant strain when connected which eventually lead to the olive slipping off. All I have to do is lower the rad by 15mm to give both pipe ends a bit of play. Wish me luck and thanks once again to all of you for your advice. I may get a professional next time but have learnt a lot doing this for myself.
