On this occasion, it is September of last year when the business was boasting a workforce larger than at any time since 1960, widely regarded as the beginning of adland's high summer. Today, that snapshot draws comparisons with Britain as it was during the summer of 1913. This was, by all accounts, a carefree period in which Britons basked in the balmy weather, unaware it would be their last before Europe was plunged into a new dark age.
Of course, it's only advertising and to compare its current state with that of a country on the brink of a bloody war is trivial. Even so, it's hard not to draw some parallels with a time of calm before a storm. Recessions have always led to agency jobs being shed in significant numbers and there's no reason to think they won't do so this time.
Nabs, the industry charity, says almost three-quarters of calls to its helpline are from agency people who have either just been made redundant or are in fear of the axe. What's more, the number of calls during the last quarter of 2008 was 179 per cent up on the corresponding period in 2007.
If there's any consolation to be had from this, it's that if redundancies are to be made by cash-strapped agencies (because they always are), recessions end (because they always do). And when the end comes, it's safe to assume that the industry will have been much changed, although not necessarily run by a much reduced workforce.
The shift in the way brands are promoted to consumers will require lots of new and different skills. Agencies will need people who can not only make sense of social media for clients, but who know how to make money out of it.
Meanwhile, it seems likely that other employment opportunities will open up if other holding companies follow the lead of WPP and move away from their traditional comfort zones to become more strategic, insight-led organisations.
Advertising may no longer be the most fun you can have with your clothes on. But maybe that's a small price to pay.