Funny things fault currents...
A while ago SWMBO turned on the light on the cooker hood, and one of the bulbs decided it was time to play lemming. Flash bang, dead cooker hood. So I replaced the bulb, still no joy. Thought, aha, it must have taken out the fuse in the plug... checked it - working fine. At that point I lost interest for months. Anyway today I located the required round tuit needed to permit further investigation. No internal fuses to be found, and volts were getting as far as the input connector. The little circuit diagram sticker in the box showed nothing else between mains and lamp save for a switch. So having extracted the switch box (and removed enough years of cooking goo to make it touchable), I pulled it apart to check the switch. Switch was fine, but the big black stain of vaporised metal inside the case was a bit of a clue! There was also a nice clean bit of PCB with no solder resist on it, and more critically, no copper either! So the bulb short had taken out about a cm of 3mm PCB track leaving the 5A fuse unharmed.
Repair involved de soldering incoming wire attached to a now completely pointless annulus, and tacking it onto the back of the board a bit further along the track. Result, happy SWMBO.