The town's coat of arms depicts the old castle that used to stand on the site of the former prison. The royal purple background represents Dorchester's status as part of the monarch's private estate, a position held since before the Domesday Book was published. The shield is divided into quarters, two depicting lions and two fleur-de-lis. These are copied from the shields of the troops from Dorset who took part in the Battle of Agincourt in 1415. The fleur-de-lis have a scattered arrangement which shows that permission for the armorial bearings was given before 1405, after which date the rights were varied by King Henry VI. The inscription 'Sigillum Bailivorum Dorcestre' translates as 'Seal of the Bailiffs of Dorchester'. The mayor has a similar seal of office, but this has the inscription "Dorcestriensis Sig: Maioris".