The unfortunate man in this advert is one Neil Innes, late of the Bonzo Dog Doo-Dah Band. I can only assume his motivations for doing this were because the royalties for "I'm The Urban Spaceman" were running out, and those for The Raggy Dolls had yet to come in. Taking in offensive Asian cultural stereotypes, a pop at the best footballer in the world at the time and blatant sexism, it remains a classic of alcohol advertising of the 1980s.
Still, we have to give credit for Greene King for admitting one thing - the only way to get people to actually want to drink GK IPA is to chain them up against a wall until delirious. If only other brewers of dubious beers were so honest