I reckon they do have some purpose... potentially encourage others to get to the polling booth and can help to swing those who don't want to 'waste' a vote. Say you're in a traditional Tory area but loads of Lib Dem banners start appearing. If you previously thought the Lib Dems had no chance, you might just start to think they're worth a pop and could actually win the seat and so you vote for them instead of, say, Labour. That's what I've always assumed the reasoning is.
Not that I'd personally want to display one for any of the f******* that masquerade as public servants these days.
Not that I'd personally want to display one for any of the f******* that masquerade as public servants these days.