The two intrepid teams leading the day's gruelling action consisted of the Abbott Mead Vickers BBDO departees Jeremy "crack serve Carr and Andy "volley Hopkinson, against Paul Gummer and Nick Crisp from PHD.
The teams spent 12 - yes readers, that's 12 - hours working up a sweat on court. All in aid of raising the final funds for AMV's charity, Big House.
They were joined at hourly intervals by volunteers who fancied themselves as La Manga Tennis School graduates and who'd shelled out £50 to play.
"Believe it or not, they actually paid for the privilege of playing with us, a shocked Hopkinson recounts.
Players from The Economist, Eurosport, IPC and Freud Communications all joined in the event, which must have seen a fair amount of rival industry bods slugging it out over the nets. "Not at all, it was all incredibly generous, Hopkinson protests, before admitting: "Well, there weren't too many rows. There were no lawyers involved anyway."
Hats off to Gummer and Crisp who, despite challenges from expert players - including the Wimbledon champion Roger Taylor's daughter - remained undefeated all day.
Still, they were given a run for their money by Lowe's Chris Thomas and also AMV's Peter Souter. "Peter had an absolute bullet serve, Hopkinson remembers enviously. "But we managed to tame them, he crows in a very unsportsman-like manner.
TBWA/London's Garry Lace sponsored £5 per ace, which turned out to be a nice little side earner for Hopkinson, who managed to score a whopping 19. "Most importantly there were three against Chris Thomas, which was particularly sweet, he says with relish.
So after raising £3,500, surely they must all have piled off to the pub to celebrate? "I'm 44. My whole body was sore, Hopkinson protests.
"But I did have a very, very long hot bath."