St George on horseback slaying a dragon as part of the Bronze centre gates of Marble Arch. 

Largely inspired by the Constantine Arch in Rome; Marble Arch was designed by John Nash after George IV defeated Napolean - as a gate to Buckingham Palace and but in 1832. 

When an extension was made to Buckingham Palace it was moved to its location (now a traffic island...) at the junction of Oxford Street; Park Lane and Edgeware Road. 

It was also a Police Station at the turn of the 20th Century! 

You can see the piece in full on Victorian Web - Best Viewed Bigger