But why?

This man has something to do with it.

Meet John Pash.

He designed the most famous tongue in history.

I was at the Royal College up to 1970, doing three years at a design course there.

When I was in my last year, the college got a phone call from the Stone's office saying would a student go along and talk to Mick Jagger about forthcoming tour?

I think the tutor was quite a sort of fan of my work, so I got the gig.

Mick said he wanted something related to more touring.

We shared an interest in sort of 1930s, 1940s tour posters, particularly French ones.

I took a couple of weeks working on the poster and brought it back to Mick.

He said, "Well, I quite like it, but I think you can do better."

And you can imagine I thought, "Oh God, I've blown it."

John drew up another version and this time the band loved it.

His poster was a triumph and before long, another project was on the cards.

They had a sort of small logo in mind for their new record label.

I got a letter and then a call, asking if I'd go and meet Mick Jagger at his house in Shady Walk.

So I went along there and had a meeting with him.

He wanted something to stand alone, something like the Shell logo on the petrol stations at the time.

And he showed me a cutting that he found in the local news agent.

The image was of the Indian goddess Kali with her tongue sticking out.

And I think it was that moment that was the real spark.

It represented, I suppose, anti-authority, it's like kids sticking their tongue out.

It's rebellious. It kind of fitted what the Stones represented at that time.

I went home and got out my sketchbook and pencils and tried to draw a disembodied tongue.

I did three or four different angles of it.

One of the rough designs seemed to be much better than the rest of them.

That's the one that I was going to recommend to Mick when we had our next meeting.

Now, some people say to me that it was inspired by Mick Jagger's mouth, but in fact, it wasn't.

I always saw it as basically a woman's mouth because I wanted to use a very strong red, obviously to grab attention.

The tongue had its first big debut on the inside sleeve of the Rolling Stones' Sticky Fingers album,

but before long, it was stamped everywhere.

These rebellious red lips became a global icon.

I sometimes get emails from people, particularly one, which, some guy had, made his girlfriend have it tattooed on her bottom and sent me a photograph,

which I thought was going a bit too far but that's Rolling Stones fans for you.

It's obviously interesting to see how many people wear the t-shirts.

When I see somebody walking down the street and I'm together with my wife,

I just give her a nudge and that's enough to say, "Oh, yes, I've clocked that."