Hendon was an ancient civil parish of around 8,250 acres (33 km2) which included Mill Hill, as well as Golders Green and Childs Hill. In 1894 it was created an urban district of Middlesex and in 1932 it became a municipal borough. The municipal borough was abolished in 1965 and the area became part of the London Borough of Barnet.
The Wikipedia page is [1]
Coat of arms described here, and Hendon Town Hall here
Film on the Charter Day here.
See also List of Mayors of Hendon