I knew this was the UK before you even mentioned the charge was in Pounds. I have never (in thirty years plus of renting / hiring cars all over the world) seen return agents so desperate to find the smallest damage as I have in the UK - specifically at MAN. I can only assume they are rewarded in some way for finding an extra way to chisel the customer. I now diligently photograph all four wheels and any other damage because of this - they will charge a stupid amount for a tiny scratch on a wheel.