Leigh-on-Sea, commonly referred to simply as Leigh, is a town and civil parish in the city of Southend-on-Sea, in the ceremonial county of Es…Leigh-on-Sea, commonly referred to simply as Leigh, is a town and civil parish in the city of Southend-on-Sea, in the ceremonial county of Essex, England. In 2011 it had a population of 22,509. Leigh-on-Sea is on the northern side of the Thames Estuary, a few miles from the open waters of the North Sea to the east, and a similar distance from the Kent coast to the south. The coastal environs of the town feature a nature reserve at Two Tree Island and a centrally located beach adjacent to Bell Wharf. At low tide Leigh's foreshore has a wide expanse of mud flats and creeks, extending offshore towards the deep water channel of the Thames. Leigh is 40 miles from central London via road and rail networks and is part of the London commuter belt.