Here’s my attempt (or, how to upset wake up most of the electorate).

UPDATE: I tweeted Kerry McCarthy to let her know about this poster:
StewartCowan @KerryMP Finally made my Cameron poster http://www.realstreet.co.uk/
KerryMP @StewartCowan That’s my least favourite so far!
StewartCowan @KerryMP It’s my least favourite too actually. No humour, just the truth! Oooh, it hurts…
I think Kerry [...]