The Flag of Sussex is the flag of the English county of Sussex. The flag was registered by the Flag Institute on Friday 20 May 2011 as a 'traditional' county flag and was certified by Chief Vexillologist, Graham Bartram. It was first flown officially on 4 June 2011 at Lewes Castle and was flown from the Department of Communities and Local Government at Eland House, London on Sussex Day, 16 June 2011.
The flag of Sussex was registered as a result of a campaign started in August 2010, under the name of Saint Richard's Flag, after the county's patron saint, Saint Richard of Chichester. The flag was slightly altered from the original proposal before its registration by the Flag Institute. The flag represents the whole of Sussex and is based on the traditional emblem of Sussex, six gold martlets on a blue field. This emblem was first used by John Speed in 1610, as the emblem of the Kingdom of the South Saxons. Today it is used by many Sussex organisations, such as Sussex County Cricket Club, Sussex County Football Association and also features on the village sign of Ringmer in Sussex. The Flag Institute manages and maintains the national flag registry of the United Kingdom, and therefore this is now the definitive County Flag of Sussex.