Undertaker Ian Kay was always fond of a Marathon bar, and when manufacturers Mars announced that they would be changing the name of the peanut-and-chocolate treat to Snickers in 1990, he decided to stash one of the last Marathons in a biscuit tin.

And amazingly, 30 years on he’s still got it. It’s a little past its sell-by date but it hasn’t melted in all that time.

Ian say he will probably keep it in the tin “until it evaporates into dust”.

Now that Mars has decided to revive the chocolate bar’s name as a nostalgic limited edition Ian decided to share his story: "I think I will get a packet of the new ones,” he said.

“I'll leave it in the tin with the others until I die.”

Ian confesses that he's 'quite nostalgic'

"I'm glad they're changing the name. It should be changed permanently. It sounds better.

"All these 20 or 30-year-olds wouldn't even know [that it used to be called Marathon].

'They would think 'why change it back?' It's what you grow up with.”

There's no denying that the newer bar is smaller

Ian, 56, doesn’t remember that much about the day he bought The Last of the Marathons, he just remembers popping it into a tin to keep it fresh: "I must have thought at the time 'I'll keep it at the bottom of the biscuit tin'.

It has been at the bottom of the biscuit tin ever since.

"One year passed, we took biscuits out, and I thought 'should I eat it?', then five years passed, then ten years..."

Thirty years on, it’s still there, and it appears longer and wider than a modern Snickers bar when laid side-by-side.

"I don't want to ruin it,” says Ian. “I'll just leave it as it is. I just don't know what it would be like inside. The chocolate might be white.

"We rarely use the tin to pass around. We keep putting custard creams on the top. [The Marathon] will stay there until it evaporates into dust.

The 'museum piece' is well past its sell-by date

"A few friends know about it.," chuckles Ian. "My sister said 'you are sad…what you are like?’.”

"I'm quite nostalgic. I don't like chucking stuff out. My Mrs will say 'I need to get rid of that'."

But Ian thinks his vintage Marathon “might end up in a museum.”