Error £1 coins

[jens coins]

Just seen this error coin on a £1 coin.
http://www.msn.com/en-au/money/markets/rare-%c2%a31-coins-worth-%c2%a3205-are-hitting-the-streets-thanks-to-royal-mint-mistake/ar-BBID4SV?li=AAgfOd8&ocid=mailsignout

[Mister T]

I was wondering what the error was - I'm not too current on British decimals but it looked fine to me.
Surprised they managed a wrong planchet on this one.