Undated 20p: how to spot the 2008 mule with no date

In 2008 some 20p coins were struck with Matthew Dent's new shield reverse and the old obverse, so the year appears on neither side. The Royal Mint says fewer than 250,000 were affected, out of 136 million 20p pieces minted in 2008-09, and that they remain legal tender.

By the Coin Scanner team · Updated 2026-10-13

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How the undated 20p happened

From 1982 to 2008 the reverse ("tails") of the 20p carried William Gardner's crowned double rose, and the year was part of that reverse design. In 2008 The Royal Mint introduced Matthew Dent's new reverses, in which sections of the Royal Arms on the 1p, 2p, 5p, 10p, 20p and 50p fit together to form a complete shield. As part of the redesign, the date moved from the reverse to the obverse ("heads"), where it was added to the legend around the Queen's portrait.

In November 2008, some 20p coins were struck by pairing the old obverse die, which had no date because the date had always been on the reverse, with the new Dent reverse die, which had no date because it was now meant to be on the obverse. The result was a coin with no year on either side. Collectors call a coin struck from two dies that were never meant to be used together a mule. The Royal Mint described the cause as an incorrect pairing of old and new dies.

How many undated 20p coins are there?

No exact figure has been published. The Royal Mint's statement is that fewer than 250,000 coins were affected, out of 136 million 20p pieces minted across 2008-09. That is an upper limit, not a count. For comparison, The Royal Mint's mintage table shows 115,022,000 dated 2008 20p coins with the new Dent shield and 11,900,000 dated 2008 coins with the old Gardner rose.

The Royal Mint has also said the undated coins remain legal tender with a face value of 20p. Like every 20p, they are legal tender for amounts up to £10.

How to check your 20p in seconds

1. Check the reverse first. You need the shield design: a section of the Royal Arms showing heraldic lions, with the words TWENTY PENCE beside it. If your coin has the crowned rose instead, it is not the mule, because on that design the year is on the reverse, split either side of the crown.
2. Turn it over and look for a year. On a correct shield 20p, the legend runs round the portrait and ends with the year at the lower right, for example ELIZABETH II D G REG F D 2008.
3. Check the legend layout. On the undated mule, the obverse has a different arrangement: ELIZABETH II across the top and D G REG F D across the bottom, with no year at all. This layout matters, because it helps you tell a real mule from a coin where the date has simply been worn or damaged.
4. Confirm the basics. A genuine 20p is cupro-nickel, seven-sided, about 5.0 g and 21.4 mm across with a plain edge. A coin that is badly worn, filed or damaged around the legend should be treated with caution.

If you'd like a second opinion, photograph both sides with Coin Scanner. It identifies the design, reads the date and gives an estimated value range.

Common mix-ups

• Old rose 20ps with a plain obverse. Crowned-rose 20ps, struck from 1982 to 2008, have a dateless obverse. That is normal, not an error. Look on the reverse and you will find the year either side of the crown.
• Other denominations. The Royal Mint's statement concerns the 20p. A 1p, 2p, 5p, 10p or 50p that seems to lack a date is far more likely to be worn, dirty or damaged, so check it carefully under good light.
• Listing prices. An asking price online is not what coins actually sell for. Look at completed sales or ask a dealer.

What makes one undated 20p worth more than another

All undated 20ps share the same error, so condition does most of the work. A coin with sharp detail and little wear will attract more interest than one that has been in circulation for years. Its value is whatever a buyer is willing to pay at the time, and any online estimate, including the app's, is only a guide. If you have a coin in especially good condition or several examples, ask a reputable dealer or a professional grading service to examine them before you sell.

Searching your change for other scarce coins? See our guides to rare 50p coins and the Kew Gardens 50p.

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