Wall warts!....the fewer the better it seems

[Barry]

The most common arrangement in the non switch-mode variety is a thermal fuse embedded in the transformer winding. It is indeed rare to find any sort of user replaceable fuse but then again it's also pretty unlikely that the thermal fuse will go unless there is a genuine problem. They are at least cheap if they do have to be replaced.....

Thanks for that Jez.

I was puzzled as they all sport the "C E" mark (not that that means much)! The charger for my camera battery is so small (about 1.5 x the size of the battery itself), there doesn't seem room for a transformer?

On a completely different tack - what do you know about the safety of those air freshners that plug into the mains? It seems odd that the heater element is only protected by the 30A fuse or circuit breaker of the ring main.