Last year, the agency began dabbling in drama, drafting in its very own playwright-in-residence - the Soho Theatre's David Eldridge. Under his guidance, four members of the GGT staff produced six plays, all of which were staged.
And that's not all. In March, the agency was at it again, using theatrical trainers to help its staff perfect their pitching abilities. These pitch clinics were the inspiration for a play, created by three Soho Theatre practitioners.
Now, GGT has turned its attention to music. Last week, at the Nabs Battle of the Bands night at the Hammersmith Palais, the agency's in-house band, Vegas, took the audience by storm and ran away with the competition.
For the record, GGT wasn't the only direct agency to impress that night.
Proximity London's band, curiously named Fractured, won the best original song prize, for a little ditty called Caravan Man (we'd love to be able to tell you that this is song about Stef Calcraft, but alas it's not the case).
So what on Earth is going on? We've got direct agencies producing plays and poetry and spawning musicians and comedians (see last week's Diary).
We've got Ogilvy & Mather getting involved in ballet. Charles Saatchi's modern art dabblings hit the headlines every other day. John Hegarty's exhibiting photographs - every bugger's at it.
It would seem that advertisers are becoming artistic.
Which raises the question: can this be the industry that gave the world "Curry's, always cut-ting prices"?