From the Wikipedia page 
Heston and Isleworth was a local government district of Middlesex, England from 1894 to 1965.
It was created an urban district in 1894 by the Local Government Act 1894. It gained the status of municipal borough in 1932.
In 1965 the municipal borough was abolished and its former area transferred to Greater London to be combined with that of other districts to form the London Borough of Hounslow.