EDITOR'S NOTE: Since we originally published this piece, we've been alerted to the fact that the poster below is currently on display as part of the London Transport Museum's Night Shift exhibition. You should check it out.

So here's a thing. An advert for the London Underground*, dating from 1928, helpfully telling users when the network was at its busiest.

Oooooooooh:

This is brilliant in two completely different ways. One is the descriptions of the sort of people travelling at each hour of the day, which mix practical information ("More Business Men", "Theatres, Cinemas and Restaurants IN") with a few wry jokes ("Not all Patrons are punctual").

There's also an interesting insight into the class system of the time in the distinction between "The Business Man" and "The Workers". And the line, "A quiet hour. London is recreating" is just lovely.

The other way in which this is brilliant lies in what this information is actually for. The real purpose of the ad is hidden in the description of the period between 11am and 5pm:

"The Shoppers and Pleasure-Seekers are now abroad, and it's the best time too, as the Business Folk are at work and there is more room in the Trains"

In other words, what we're looking at here is an attempt to use cutesy language to convey actual statistical information about the best time to travel. Effectively, it's an 87 year old piece of data journalism.

At the time this ad was published, incidentally, the Tube was carrying 1.1m passengers a day. Today, it's anything up to 4m. The network is bigger now, of course – but it isn't four times bigger. Nice going, guys.

*(EDITOR'S NOTE: The following is no longer relevant, since we have now verified the image, but we'll leave it here for posterity. So:)

Mildly embarrassing disclaimer: we've not actually been able to verify this image. It appeared on Reddit with no explanation of where it originally came from, and its earliest appearance on the internet seems to be this Tumblr.

But we're at least 98 per cent confident it's real. Partly that’s because it looks real: this was the sort of ads that London Underground used to specialise in back in the day, and the image looks original.

But mostly it’s because this would be a very odd thing to make up. Even if you were of a mind to hoax the internet's booming community of London transport geeks (hi, guys), this just isn't how you'd do it.

If I wanted to hoax you lot I'd probably make up plans for an unbuilt tube line – one through Dalston and Hackney, with a map and everything – and then claim it didn't get build because the locals opposed gentrification or something. But that's just me.