But these are no traditional street artists or Turner-prize-winning youngsters.
No, enter a number of specially selected JWT veterans, who were wined and dined before having a Magic Marker thrust into their hands and being told to get creative on the walls of the prestigious building, which has housed residents including old blue eyes himself, Frank Sinatra, and Merle Oberon.
First up was Denis Lanigan, the former managing director who ran the agency in the heady days from 1966 to 1974, who inscribed a very polite "Thanks for the memories". He was followed by other eager scribblers, including Doug White, who "was 'ere and enjoyed every minute of it - R.I.P". Er, quite, Doug.
JWT has, perhaps unwisely, thrown wide its doors to allow other former employees in to pass on their fondest regards, as well as the existing payroll. One former JWT executive recalls his first office back in 1957.
"Admittedly, it had its disadvantages. For one, it was a converted gents' lavatory, and in order to assume a business-like pose behind my split teak desk I had to sit astride a blocked off U-bend,
We've yet to hear if other former JWT staffers, such as David Bowie, Martin Amis, Julie Christie or Fay Weldon, will be taking up the challenge to pen a few words about their previous incarnations in the world of advertising.
Indeed, while we haven't noticed the queues amassing around Berkeley Square, it is probably best to get down there before the demolition boys move in on 3 May as, sadly, the invitation doesn't extend to the new pad in Knightsbridge Green.