A student from the UK found a coin "from the future"

Sarah Legg was handed a coin along with change after paying for lunch at college, and she noticed an unusual design.

Emma said:

"I was just eating in college and thought the coin looked very shiny, so I took a closer look. I thought I was in the future with the signs that were there. Where the date of manufacture was written 2011. I was a little shocked, to be honest, and showed it to all my friends. It looks like the Royal Mint made a mistake."

Coin experts are puzzled by the find.

Rob Davies, from Portsmouth, Hampshire, said:

"It's very unusual and special, and a young girl should keep it. I can't name their cost, but they are very special and similar to the 20p issue issued a few months ago."

Royal Mint spokesman Nick Scargill said:

"It's unusual, but they are perfectly legal tender. This is something special."

The silver coin depicts one of 29 designs created by members of the public for the Royal Mint ahead of the 2012 Olympic Games.

Now the 17-year-old forensic science student hopes to sell it to coin collectors to help pay for university tuition after she leaves Fareham College in Hampshire.

However, today the Royal Mint announced that the coins have been gradually released into circulation since October, so people should expect to start finding them in change now – and their cost is only 50 pence.

Previously, there were only 16 designs of the 50p coin, created in 1969.