Surely the increase in people dropping off at the long stay car park to avoid a £5 charge will be minimal? Most people have spent hundreds / thousands on a flight or holiday and so the cost will just be "oh well - annoying, guess I'll pay it" and get dropped at the terminal door rather than playing around with buses and luggage.

A cab for me is £50 and I certainly won't be contemplating swerving by the long stay to avoid that £5.