A 1933 British pattern penny realised a world record £72,000 ($103,708) in a sale at Baldwin's in London earlier this month.

It smashed its estimate of £40,000 ($57,622) by 80%, becoming the most valuable copper or bronze coin ever sold at auction.

Only four of the 1933 pattern pennies were made

Only around six or seven pennies were issued in the UK in 1933, as the Bank of England held enormous stocks in reserve from previous years.

One of the reasons they were minted, if only in such small numbers, was because at the time it was customary to bury full sets of a year's coins beneath the foundations of public buildings.

The example that sold, however, was even rarer than these standard 1933 pennies.

It was designed by a French engraver named Andre Lavrillier, who was considered one of the most talented artists working in his field.

At the time the Mint was having issues with ghosting (where unwanted areas of the die are transferred to the surface of the coin).

Lavrillier was recommended to the board of the Royal Mint as someone who could fix the problem.

A total of four pennies were produced to his design (including the present specimen), but the board was unimpressed with the result and canned the project.

A spokesperson for Baldwin's told the BBC: "No other bronze coin has ever come close.

"I think the last was in the region of £15,000 [$21,606]."

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