Tolley’s Tax Handbook
A big yellow book with onionskin paper, that smells vaguely of chicken soup, and contains everything a tax lawyer could possibly need when contemplating the eternal verities.
For the rest of us, a garish doorstop or something to prop your VDU up on if you can't find a phone book. But it’s somewhat pricey method to prevent slouching at your desk: that’s is a couple of hundred quid’s worth of tax ninjadom you've got right there, soldier.