Roger,
I've tried Command-Option-O-F no joy. tried also with the screen face down, upside down, sideways etc, still stuck. No joy with the visa card, amex card, cash card, NHS card or drving licence either.
.
It seems that removing the drive is quite straight forward and as it is looking increasing likely that I'll have to replace the whole iMac I am not too worried about damaging it. It would be useful to see your Flikr photos but I get the folloowing error "Ce n'est pas la page que vous cherchiez" or "this is not the page your qre looking for".
cheers
Andy