Post Office Directory
Kellys had a long association with the Post Office, creating maps and Directories for them from 1845 to late in the 19th century.
There is also an 1888 Kelly's map, that really changes very little.
Scale correct at 10 miles = 140mm, or 1.8 miles/inch, ie 1:115,000.
Railway lines shown include Thorpe-le-Soken to Clacton (opened 1882) but not Southend to Shoeburyness (opened 1884).