Royal Mint mooted 60p Diamond Jubilee coin
A six-sided 60p coin was nearly made to mark the Queen's Diamond Jubilee, newly released documents show.
The Royal Mint designed the coin and carried out research which found support for the concept.
The idea was recommended to Chancellor George Osborne to commemorate the Queen's 60 years on the throne.
But papers from the Royal Mint Advisory Committee show the plan was shelved as the commemorative coin programme was already "sufficiently comprehensive".
The plan came to light following a Freedom of Information request to the committee by the Press Association.
The Royal Mint has not released an image of the proposed coin, which would have been a commemorative collectable, rather than in general circulation.
The letter to Mr Osborne, dated 24 February 2011, said an event of "huge national importance" should be marked with more than one type of coin.
"The proposed coin would be a six-sided bi-colour coin with round of nickel-brass and a shaped outer of cupro-nickel," it read.
The recommendation, which also included a Diamond Jubilee kilo coin, added: "It is judged that the issue of these new United Kingdom coins will be free from any risk of controversy and will, in fact, meet with wide general appeal."
But the 60p piece was not included in the coins released for the Diamond Jubilee in 2012, which sold thousands and included different versions of a £5 coin.
Gerry Buddle, a specialist at the London Numismatic Club, said the 60p coin would have had a "certain curiosity interest" but he suspected it was rejected by senior staff at the Mint for being "too gimmicky".