The flag is ancient in origin and features three notched Saxon seaxes (cutlasses) on a red field.

A Restitution of Decayed Intelligence, written in 1605 by Richard Verstegan, referred to the Anglo-Saxons bearing a standard of "Three seaxes argent, in a field gules".

[1] Similarly, cartographer John Speed included the flag in his 1611 atlas The Theatre of the Empire of Great Britaine.

[1] By 1815 the flag had become synonymous with the county, appearing as the masthead on the Chelmsford Chronicle and as the logo of the Essex and Suffolk Equitable Insurance Society.

[1] By the late 19th and early 20th centuries, the flag saw widespread usage throughout the county, appearing on buildings and infrastructure in numerous settlements.