The Fairlop Loop was a 6.5-mile (10 km) branch line of the Great Eastern Railway (GER). It opened to freight on 20 April 1903 and to passengers on 1 May 1903. It once connected Woodford on the Ongar branch to Ilford on the Main Line, with an eastward connection for goods, excursions and stock transfers to Seven Kings. Today it is the greater part of the Hainault Loop on London Underground's Central line.
The GER built the line to foster suburban growth in Edwardian Ilford and Chigwell; the results were mixed. Hainault station had so few passengers that it closed between 1908 and 1930. The loop passed to the London and North Eastern Railway (LNER) in 1923 after the grouping of railways into The Big Four. The LNER added a station at Roding Valley in 1936 to serve a housing development. Most of the route transferred to the Central line of the London Transport Executive (LTE) during 1947 and 1948 as part of the war-delayed New Works Programme. The transfer brought fourth-rail electrification to replace steam and construction of a deep-level line connecting Leytonstone on the Ongar branch with Newbury Park on the loop, together with severing connections between Newbury Park and Ilford and Seven Kings.
First to go was the westward curve between Newbury Park Junction and Ilford Carriage Sidings Junction, on 30 November 1947. The other connection to Seven Kings West Junction was goods only and survived until 19 March 1956. The whole triangular junction disappeared under expansion of Ilford carriage sheds in 1959. Goods trains operated by British Rail continued using the loop via Woodford as far as Newbury Park until 4 October 1965. A short turn-back siding was provided on the former track-bed south of Newbury Park: after goods trains were withdrawn it was used by engineers' trains until 1992.