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
Hornchurch and Upminster (UK Parliament constituency) of Havering: Hornchurch and Upminster (UK Parliament constituency) Hornchurch and Upminster is a constituency represented in the House of Commons of the UK Parliament since 2017 by Julia Lopez of the Conservative Party. The easternmost seat in Greater London, this seat was created by merging two of the three old constituencies comprising the London borough of Havering, specifically Hornchurch and Upminster. These two seats were lost by the Conservatives in Labour's landslide 1997 victory, but Upminster was one of the few Conservative gains in 2001 and Hornchurch was lost by Labour in 2005; this area is now very safe territory