All good guesses so far, but the Whiskey is safe.
The ignition was the second place I looked. Having spent £150 and half a day installing a ground anchor and BFO chain, I now actually prefer the chain lock to the ignition when at home, but it wasn't there either.
The dog poo was also a possibility, but experience tells me the gestation period of a Collie-Alsation cross pupy is more like 24-48 hours, so that idea was out by Wednesday (although we did find the dish cloth- yuck).
I don't have trouser turn up's or a beard, but there is time if they'll trap anything useful.
Pockets are the one thing I'm good at. Years of travelling to dodgy places means I do keep the same thing in the right pocket when I actually use them. In this case failing to use them lost the key.
The washing machine/hoover ideas are closest but no cigar.
Answer tomorrow.
Andy