Went the plug on the microwave as I was about to heat up some cottage pie. I replaced the fuse and "Caboom!" it went again..... right, I thought, this needs some serious investigation.
I checked the plug for loose wires, no problem, then off comes the main housing cover and there lies a sugarspoon very neatly welded across some terminals. I have no idea how it got there but it is now removed and the thing does not go "Caboom!" any more, trouble is I cannot find the manual so have no idea how to set the clock!
I will just have to do the "cook till piping hot in the middle" thing for a while.