So I'm washing some birds mess off the car with my wash mitt, then I put that back in the bucket and as I use a watering can to run some clean water over the door, the car unlocks!
I guess this is because I have the keys in my pocket and the car senses something on the inside of the handle as the water passes over it? I've never had a keyless entry before so assume this is normal behaviour, lucky I didn't have my headphones on as I might normally washing the car as it would have stayed unlocked without me noticing.
