The Royal Shield £1 coin, struck from 2008 to 2015 is no longer in circulation, all round £1 coins were replaced in 2016/2017 by the new 12-sided Nations of the Crown £1 coin.
The coin design by Matthew Dent shows a depiction of the Shield of the Royal Arms. The edge inscription reads DECUS ET TUTAMEN.
Total circulation mintage: 374,139,270 coins (2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015), since demonitisation on 15th October 2017 - it is likely that many of these have now been melted down to create new coins.
Like all round pounds, the Royal Shield £1 is no longer legal tender, but can still be paid into most banks at face value.