In 2009 the Silver Series Royal Mint Big Ben £5 Crown I designed was been
placed inside the movement of the Great Clock and will play an essential role
in maintaining its famous accuracy.

The change-over forms part of Big Ben's 150th anniversary celebrations, with the new £5 Crown, one of the official London 2012 licensed coins, replacing some of the pre-decimal pennies which have acted as weights inside the clock since 1859.

 This is the first time any of the coins inside the clock have been changed.