Heraldry and medieval towns were very much linked as towns and cities used heraldic devices to express characteristics associated with them. Some heraldic shields show the story associated with that town - such as Colchester, Stepney and Bury St. Edmunds.
The earlier heraldic devices for more ancient towns wanted to link themselves to the king to demonstrate their loyalty. It was usual for towns to have a lion somewhere in its heraldic device - the city of York had five gold lions on a background of a red cross, thus linking itself to the monarch and to the patron saint of England, St. George. The Cinque Ports that were found around the southeast coast also used the lion to show a link between themselves and the Crown. Each Cinque Port provided ships for the defence of England and by rationale, therefore, protected the king. Cinque Ports developed a heraldic process whereby they divided a shield exactly in two by a vertical line going down the middle of a shield. On one side were half the body of a lion while on the other half of the shield was a charge that depicted that port. Sandwich, a Cinque Port, had three half lions on its shield and three half warships joined in the middle. Great Yarmouth - not a Cinque Port but run by the Cinque Ports Corporation - had three half lions on it and three half fish (the tail ends). While this created a somewhat curious combination, it demonstrated the town's loyalty to the king and its importance as a fishing port. The shield of Bristol was more of a one-off picture that showed a ship at sea - Bristol was a major port in the Middle Ages - with a castle on a cliff top to signify the city's importance to trade.
Towns with a strong link to abbeys or monasteries had heraldic shields that reflected this, many incorporating a mitre or cross.
London had a sword on its shield and this represented the sword that killed St. Paul, the patron saint of London. Stepney, to the east of the City, had two tongs on its shield along with a ship that indicated the importance of shipping to Stepney. The tongs were those used St. Dunstan to pinch the nose of the Devil.
The heraldic shield of Colchester had a rough cross on it with three crowns - one at the base of the cross with two either side of the horizontal branch of the cross. The crowns demonstrated the town's loyalty to the monarchy while the cross was a reference to Helena, the daughter of Coel (who gave his name to Colchester), who discovered the cross of Christ while on a pilgrimage to Jerusalem. Helena built a church in Jerusalem to preserve the cross and for this reason was effectively commemorated in the heraldic shield of Colchester.
Bury St. Edmunds heraldic shield had three crowns on it with two arrows going through each crown. The crowns represented the last king of the ancient kingdom of East Anglia - Edmund - while the arrows represented his death at the hands of the Danes when he refused to give up his Christianity.