The makers of a new Monopoly game for Canterbury are counting the cost of an embarrassing gaffe – after putting a picture of Rochester Castle on the board.

Winning Moves UK unveiled the long-awaited edition in the Cathedral city today, but included the Medway site alongside some of Canterbury’s top landmarks.

Bemused Etienne Donzelot was among those quick to spot the error, commenting on a picture posted on Twitter: “Why is Rochester castle on there?”

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The 11th century fortress takes pride of place at the top of the board, next to Canterbury Cathedral, which hosted the red carpet launch this morning.

It is not yet known which Canterbury site makers thought they were featuring or how many of the board games have been made.

Winning Moves spokesman Graham Barnes said: "We apologise for this and the montage will be corrected on the next print run."

But Winning Moves had hoped the edition would be popular with people shopping in the run-up to Christmas.

Among the landmarks on the board are Canterbury Cathedral, which has landed the top spot of Mayfair, and the Marlowe Theatre, which sits on Coventry Street.

Kent County Cricket Club’s headquarters, the Spitfire Ground St Lawrence, grabs a key location in part of a three-strong leisure set, while the Kentish Gazette has fittingly bagged the Fleet Street spot, with our radio station kmfm also making the board.

The honour of opening and playing the first game of the new board fell to eight-year-old Leila Webb, her brother Lucas, 10, from Canterbury and Kitty McAllister, 10, from Littlebourne.

They won a competition to be VIPs (very important players) for the day.

Earlier today, Mr Barnes said: "It's been a family classic since 1935 – so it’s pretty fitting, then, that a sister and brother will later this week officially launch the Canterbury edition of Monopoly.

"At exactly the same time as the board is launched the game goes on shop shelves."

The new Canterbury Edition is available to buy online and at all leading stores, including Fenwick, Waitrose, Waterstones, WH Smith and The Works.

Earlier in the year, when news of the board was announced, the public was invited to vote as to which Canterbury property landmarks should be chosen to swap places with the famous London streets. More than 7,500 votes were cast in all.

Video: Monopoly bosses are red-faced after adding a picture of Rochester Castle to its Canterbury board game

The city beat competition from Tunbridge Wells, Margate, Maidstone and Dover to have its very own board.