Bronze 1973 Error 10p

Item Description

Error 1973 10p With Letter - 1973 large-sized UK 10p coin, struck in bronze alloy, rather than cupronickel, accompanied by a 10 December 1974-dated letter from The Royal Mint, confirming the wrong planchet error. The coin tests as 97% copper with 2% zinc and a small amount of tin, similar to a contemporary 2p, but somewhat heavier at 9.72g. This is still lighter than a 1973 10p which should weigh 11.31g. A mysterious piece.

This unassuming Ten Pence coin looks like a 2p at first glance.

That's because it was struck in the wrong metal, as an old letter from The Royal Mint confirms.

Struck In The Wrong Metal

Before 2012, 10p coins were made from cupro-nickel, with tests on standard 10p coins from this period indicating an alloy of around 76% copper and 24% nickel.

XRF testing reveals that the error coin is made of 97% copper with 2% zinc and a very small amount of tin.

We are unaware of any UK coins made with such a high percentage of copper in the last 150 years.

Old Large-Size 10p Coin

The size and weight of 10p coins were reduced in 1992. Coins struck before this date measure 28.5 millimetres in diameter and weigh 11.31 grams.

This 1973-dated coin is the correct diameter but weighs significantly less than it should, at 9.72 grams, a fact that might be accounted for by its non-standard metal composition.

The design is the standard one used on Ten Pence coins at the time, displaying a crowned lion on the reverse, paired with Arnold Machin's portrait of Queen Elizabeth II.

Letter From The Royal Mint

In 1974, the owner of this 10p wrote to The Royal Mint to query its unusual appearance.

Their 10 December dated reply, which accompanies the coin in this lot, reads:

'This coin was produced at the Royal Mint but was struck, inadvertently, on a bronze coin-blank intended for another denomination.'

This appears to confirm the coin as a genuine UK issue with a notable error: one that we have not seen before on this date and denomination.

The only similar coin sold at auction was a 1971-dated bronze 10p weighing 9.92 grams that sold in June 2021 via London Coins, suggesting that the same error occurred in multiple years.

Sell With The British Error Coin Experts

RWB Auctions are the UK experts in modern error coins and rare Royal Mint issues. If you have a similar coin or another unusual piece of currency you are interested in selling at auction, we strongly encourage you to email coins@rwbauctions.com for a free, no-obligation valuation.