So, the weatherproof extension lead arrived from Toughleads yesterday, and I installed it this afternoon. Looks high quality and it wasn't hard to sort out (in fact, the only problem I had was with the ratty brickwork of the old garage - I had to use a couple of rawlplugs and screws, which is why the cable isn't as straight as I might like, but it is secure). Hopefully it'll do as a temporary fix for the M3 if/when it arrives, and I'm sure would be fine for the Leaf if I/we ever get the charger at the front of the house socketed or upgraded. Failing that, I can always plug the pressure washer in...!