I can get you on if you want - I'm sitting on (not literally) the National Statistics Postcode Directory.
Its a huge database containing every postcode in the UK linked to numerous other geographic identifiers such as Government Office Region, Census Wardcode and EU Parliamentary Constituency. It far surpasses the Da Vinci Code in plot, character and literary skill. And I say that as someone who saw the review of it on Newsnight Review and who would like to kill all the reviewers one by one making sure that the next victim knew where they stood in the queue.