Bluesky users investigating which font was used in the ads, which were ubiquitous in the early 2000s, unearthed evidence that it was an “illegal clone” of a copyrighted font.

PDF files from the official campaign website suggest that a font called XBand Rough was used — a rip-off from Just van Rossum’s FF Confidential font.

Mr van Rossum told Sky News: “I had known about the ‘illegal clone’ of my font before, but I didn’t know that that was the one used in the campaign.

“The campaign has always had the wrong tone, which — to me — explains the level of fun that has been had at its expense.

“The irony of it having used a pirated font is just precious.”