A rare Olympic coin that was designed by a nine-year-old child from Bristol has sold for 400 times its market value.

Florence Jackson was only nine years old when she beat 17,000 entries to win a Blue Peter TV competition.

As part of her prize, the child's Olympic coin design was put into circulation and she became the UK's youngest coin designer.

Florence's coin shows a high jumper with the logo of the London Olympic Games above, and is one of 29 different collectable designs created by members of the public.

But the Bristol girl had no idea at the time how much her design would one day be worth.

Going under the hammer at RWB Auctions in Royal Wootton Bassett on September 25, her rare 2009 50p coin has sold for £200, which is 400 times its market value.

The rare coin was designed by Florence Jackson, who is now 24 years old.The rare coin was designed by Florence Jackson, who is now 24 years old. (Image: RWB Auctions) “The standard 2011 Athletics 50p is a great design with 2,224,000 coins released into circulation," said Jon White, from RWB Auctions.

"But the 2009 coin is much rarer though with just 19,722 coins minted which is much lower than other well-known rare 50p coins like the Kew Gardens.

"Because these coins are scarce, they have been known to sell for £200 or more.”

Change checkers across the UK are already on the hunt for more of these Olympic 50ps.

Athletics 50p coins dated 2011 are not worth much more than 50p, but finding a 2009 variant could earn you hundreds at auction.