The area's name arises from 'Hangra', meaning a wooded slope in Old English. In November 1905 Ealing Town Council gave approval for expenditure of £4,600 for a sewage system and £4,400 for purchase of land at Hanger Hill. This was the result of an application made by the owner of the land for drainage works to be carried out to provide for the houses he wished to develop over his estate. The Council initially was not prepared to accede to this in advance of the houses being built, but then made a proposal that they would undertake these sewage works, costed at £9,000, in return for conveyance of a piece of land valued at £4,400 in order to create a recreation ground. One Councillor opposed the scheme on the grounds of upkeep costs, and also claiming another recreation ground was unnecessary since there were two parks in the borough 'either of which would hold the entire population of Ealing'. However, by 1907 the new park was fenced with iron railings and had entrance gates, paths formed, seats provided and shrubbery borders completed. The Council's review of 1907 reported that 'many people have taken advantage of the glorious view to be obtained from this, one of the highest points in Ealing'.

The park included a fragment of oak woodland to the west. It is a dramatic site with fine views; Leylandia are dotted over the slopes with some good horse chestnut and oaks on the grassland. There are ornamental shrubs along the walks, with holly, yew, berberis and magnolia in the central area where there is a modest hexagonal wooden shelter. The boundary today has post and rails to Hillcrest Road. A pitch and putt course was set up on lower land to the north.

Hanger Hill House, a late C18th house built for the Wood family, who owned large tracts of land in Ealing, was on the east of Hanger Lane; it was let to Sir Edward Montague Nelson from 1874-1901 and the grounds were then a golf course from 1901-1930, after which the site was sold and developed as Haymills Estate from 1933. Woodland opposite Hillcrest Road's junction with Hanger Lane may be a vestige of its grounds.

To the west of the park across Fox Lane is now a Nature Reserve, a remnant of ancient woodland that was later part of the site of Fox or Foxes Reservoir. When the reservoir opened in 1888 the site was closed to the public and the woodland allowed to grow undisturbed. Built for Grand Junction Waterworks and with a capacity of 50m gallons of water, Fox Reservoir was on the site of Mount Castle, said to have been an Elizabethan watch tower. It was named after Edwin G Fox, Chairman of the Grand Junction Waterworks Company who officiated at the opening ceremony. It was later taken over by the Metropolitan Water Board, established in 1902. The reservoir was drained in 1943 to prevent it being used as a navigational aid by nocturnal bombers in WWII, and in 1949 the land was purchased for public open space by Ealing Council; the present plateau was created when the remaining basin was filled in between 1969-72. Initially a flower-rich meadow, this was later used as playing fields in 1982. In 1983 the London Wildlife Trust was given permission to manage Fox Wood and the meadow as a site for conservation, and it was declared a Local Nature Reserve in 1991.