The Metropolitan Borough of Deptford was a metropolitan borough in the County of London between 1900 and 1965, when it became part of the London Borough of Lewisham along with the Metropolitan Borough of Lewisham.
The borough covered the same area of the ancient parish of Deptford St. Paul, which had been separated from the neighbouring parish of Deptford St. Nicholas to its north in 1730. The rateable values of the two parishes had been roughly equal when they were separated, but St. Paul contained all the farmland to the south, the majority of which was built on over the next 170 years.
When the Metropolitan Borough was created in 1900, consideration was given to reuniting the two parishes, but a closer equalisation of rateable value (property tax) was served by uniting St Nicholas parish with the borough of Greenwich to the east.
The growth of the London conurbation had reached Deptford by the end of the eighteenth century but it had been a large industrial town well before this time: the Royal Docks and the Victualling Yard, which provisioned the Navy, and the various private dockyards, meant it was a prosperous and cosmopolitan town.
The Wikipedia article on the town of Deptford gives a much better picture of its history from its fishing village era, through the dockyard building era during the reign of Henry VIII and on through the 17th and 18th centuries.