Arms : Gyronny Vert and Gules a Saxon Cross per saltire and quarterly Argent and Or.
Crest : On a Wreath Argent Vert and Gules a Sea Wyvern sejant Argent winged Or grasping in the dexter paw an Ostrich Feather palewise also Argent penned Gold; Mantled Vert doubled Argent.
Supporters : On either side a Sea Wyvern Argent winged and gorged with a Saxon Crown Or the Compartment composed of Graded Pebbles proper.
Motto : 'SERVICE WITH HONOUR'
The arms were officially granted in 1990.
The shield is divided into eight pieces representing the three former boroughs and one urban district (red) and the four former rural districts (green) which were combined to create the new District Council in 1974. The Saxon Cross symbolizes the ancient kingdom of Wessex, a name which is synonymous with the novels of Thomas Hardy. The four points of the cross represent the four ancient monastic foundations of Abbotsbury, Cerne, Forde and Sherborne.
The sea wyverns are appropriate to a district which was once the centre of the Kingdom of Wessex (whose kings used a golden wyvern as their emblem) and with traditional maritime associations. They are gorged with Saxon Crowns as are the dragon supporters in the arms of the Dorset County Council. The Ostrich feather quill pen refers to both Thomas Hardy and William Barnes and is an incidental allusion to the west Dorset estates of the Duchy of Cornwall, two such feathers occuring also in the arms of the Duchy.
The compartment of graded peebles is a representation of Chesil Beach.
Before 1990 the council used the image below as an unofficial coat of arms. Unfortunately I do not have a coloured version hereof.
Literature : Image and information provided by Laurence Jones.