The Sprouts Of Wrath by Robert Rankin
Amazing, but true: Brentford Town Council, in an act of supreme public-spiritedness (and a great big wodge of folding stuff from a mysterious benefactor) has agreed to host the next Olympic Games. The plans have been drawn up, contracts, money and promises are changing hands. Norman's designed some stunning kit for the home team, and even the Flying Swan's been threatened with a major refit (gasp!). But something is very wrong...primeval forces are stirring in ancient places...dark magic is afoot in Brentford and someone must save the world from overpowering evil...
...Jim Pooley and John Omally, come on down!
This must be the daring duo's toughest assignment yet. No longer can they weigh up the situation over a pint of large at random moments during the day. No, this time, to save the world as we know it, the lads must contemplate - nay, undertake - the most horrible, the most terrifying, the heretofore untried - REGULAR EMPLOYMENT!!!