Middlesex is one of the 39 traditional
counties of
England. It included the City of
London, although this was self governing from the
thirteenth century. London's northwestern suburbs steadily covered large parts of Middlesex, especially following the coming of the railways. In
1965, Middlesex ceased to exist for administrative purposes, when most of it was incorporated into the new county of
Greater London except the parish of
South Mimms[?], which was given to
Hertfordshire, and the area around
Staines, which became the
Spelthorne[?] district of
Surrey.