Lee wrote:
Seems to be a recent random, and admittedly slight, smell of gas in our
flat. Thought at first it was only with the boiler on (only thing that's
gas), but it isn't.
I did a drop test, which showed no leaks, and got a Corgi to do one as
well (and check the flue) - again no leaks.
Went round *every* visible joint with leak fluid and still can't find
anything.
I've had a look back through the archives and I'm pretty sure it's not
electrical or dead rodent

So... any ideas what else to check?
Would it be worth trying to find/rent ask someone with a gas sniffer?

Haven't you rung Transco on their emergency gas-leak number? They'll be
round faster than a rat up a drainpipe, and will find what the problem
is, whether it's next door or not.

David