Cabbies for Boris

"Don't worry I've already been canvassed," I was told on the phone today. I had been doing my patriotic duty ringing residents asking them to vote for Boris. "Oh, I'm so sorry," I replied. "We haven't got you marked down." "No, no. I haven't been canvassed by the Tories. I was in a taxi and the driver went through all the reasons I should vote for Boris and by the end of the journey I promised I would."
I can't afford to take taxis very often but I wonder if the Boris campaign is being given a crucial boost by this second layer of unofficial canvassing.