Guido has drawn attention to another innovative piece of campaigning by the Boris campaign, namely, Back Boris taxi receipts:

It’s stuff like this that sets a campaign apart, and gives it a real grassroots feel. From Back Boris Oyster Card holders to taxi receipts is setting a gold-standard in inovative campaigning.

Incidentally you can order your own Back Boris Oyster Card holder by emailing info@backboris.com.