Noted in the press recently (the Times first reported it on 30/1/18) there has been some exposure for the discovery and forthcoming auction of a 2017 £1 coin made of a single piece of golden brass coloured alloy.
About 7 or 8 of these error £1 coins are known to me and I examined one in the flesh just after Christmas 2017. Despite what it says in the press and on certain websites, I’m convinced the coins have not been struck on old pre-2016 single metal blanks, as for that to be the case, the weight of them would be – within a gnat’s whisker – about the same as the older round pound coins – and it isn’t, it’s not even close. The claim that an old round pound blank was stuck in the machinery for months or years is also very unlikely indeed.
The monometallic £1 coin I examined weighs 8.7g, which is exactly in line with the normal weight range of the new 12 sided £1 coin. Old £1 coins were heavier, at about 9.5g. The circumstances that have led to these error coins is in my opinion due to a brass piece intended to make up the outer ring-piece failing to have a hole punched into it and somehow being struck as a coin, without the intervention of any nickel plated centre pill-shaped piece, which should be introduced and pressed into the brass coloured ring by the dies, at the same time as the coin is struck with the design. A number of £2 coins for which this error has also occurred are also known and have been examined (see my introduction to error coins post) and the same kind of errors are also known concerning foreign bi-metallic coins.
Despite the incorrect information, this particular mono-metallic coin does indeed seem to be extremely rare. It is a very recent coin though, so potentially more will come to light – especially now that people are aware of them and will look more closely. It’s interesting that as far as I know, no single metal 2016 coins have been discovered.
The Check Your Change admin is Mr C H Perkins, publisher of numismatic publications in printed and eBook format. Author of "Collectors' Coins - Decimal Issues of the UK" and other books on British coins and related subjects.