"Dubba's used the pressure from the spare tyre to pressurise the washer bottle, a bit like having a Supersoaker for a screen wash. Minis had a hand pump."
Wow you learn something new everyday! What a silly idea.
No worse than frantically jabbing at button with your thumb while peering through a salt splattered screen. A really silly idea would be blowing exhaust fumes in through a vent under the back seat under the pretence of providinng heating.