Found this in Scarthin Books in Derbyshire (well worth a look if you're round that way). Haven't read the book but Steadman seems to have got the cover right judging by the blurb:
'Here amongst thirty tons of confiscated white paper lives a squat, monstrously endowed customs officer of sixty, Roman Wachholder. Up on the hill in a hygienic, sound-proof house lives his friend and mortal enemy, Ossias Wurz. While the valetudinarian Wurz spends his days systematically cleaning, disinfecting and redecorating his house, the earthly, guilt-ridden Wachholder spends his crazily concocting poison-pen letters to drive him out of it'.
Darkly humorous, surreal, existentialist nonsense meets it's match in Steadman's erratic and instantly recognisable linework.