Terry, who owns Northern Photo Electronics, and whom I've always taken camera problems to, was scratching his head to work out what was causing the problem. The hot shoe was not loose and the flash itself seemed Ok. It sat on the counter as he pondered, then suddenly a lightbulb lit over his head

Pointing at the hotshoe, he said "Look at that, thats the problem" Well I could barely see anything wrong, but he dashed off to his workshop and came back with a cotton bud soaked in alcohol. There was dirt on one of the terminals, which he proceeded to clean off. The flash went back on and hey presto, it all seems to work OK.
To say I was relieved is a bit of an understatement, and the fact he wouldn't take anything for his time and trouble was even better.
I once derided an Olympus user who was banging on about loosing his plastic blank that slots into the Oly hotshoe. I'm thinking now that perhaps they are not such a bad thing if they keep your terminals dirt free
