It’s not Essex, but this is Genoa who share the same flag of St. George. Indeed, there’s a strong line of argument that the English took this flag from Genoa and the Duke of Kent said in a speech in the city in 1992 that:
“The St. George’s flag, a red cross on a white field, was adopted by England and the City of London in 1190 for their ships entering the Mediterranean to benefit from the protection of the Genoese fleet. The English Monarch paid an annual tribute to the Doge of Genoa for this privilege”.
The history for all of this is a little disputed and quite controversial, but there is certainly a shared lineage of sorts.