It really annoys me when I see a London phone number written as 0207 123 1234 or 0208 123 1234.
As pedants, you would already know this, and I may be preaching to the converted, but isn't the London area code 020, so the number would be 020 7(or 8)123 1234.
When I see a number written "wrongly", I want to change it!
Does this get anybody else's goat up?