Fairlop Loop

From the Wikipedia page

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.[2] It connected Woodford on the Ongar branch to Ilford on the Main Line, along with an eastward freight connection for freight, excursions and stock transfers to Seven Kings. Today it is the greater part of the Hainault Loop on London Underground's Central line, the remainder consisting of a 4.1-mile (6.6 km)[3] deep-level underground line (opened 14 December 1947 connecting Newbury Park on the loop with Leytonstone on the Ongar (now Epping) branch.