Circle line (London Underground) with the other London Underground sub-surface lines: the Hammersmith & City line from Hammersmith to just before Aldgate; the Metropolitan line from Baker Street to Aldgate; and the District line from Tower Hill station to Edgware Road station. The line is electrified with a four-rail DC system: a central conductor rail is energised at and a rail outside the running rail at , giving a potential difference of . The running rails are not electrified. Much of the double track railway from the Hammersmith terminus to Westbourne Park station is on a high brick viaduct. East of Westbourne Park the
Upminster in Great Warley. Land for Upminster Park was purchased by the parish council in 1929. The town forms part of the Hornchurch and Upminster UK Parliament constituency, and is covered by the Havering wards of Upminster and Cranham. The current MP is Angela Watkinson. Each ward elects three councillors to Havering London Borough Council. All six councillors elected in 2010 for the two wards were the Upminster and Cranham Residents' Association candidates and the area is unusual in that the residents' association is strongly active. From 1945 to 1974 Upminster formed part of the Hornchurch constituency and from 1974 to