When I moved to London and opened up a Lloyds Bank account (then Lloyds TSB), I was confused to find they did not consider my office postcode W1F 7RB valid. I poked at it a bit and found some programmer assumed that the first half of a UK postcode was \w+\d+. The hilarious part was the branch I was opening an account at was in W1S, so their form wouldn't even take their own postcode.