the late 1950s and mid-1960s using the Mark 1 series under the BR 1955 Modernisation Plan to , extended to in 1974 using the Mark 3A range. : see Northampton loop. : see Rugby–Birmingham–Stafford line. to . to Manchester Piccadilly: see Stafford–Manchester line and Crewe–Manchester line. The "Abbey Flyer" (Abbey Line) was electrified in 1987–88 by Network SouthEast. in 1989 (from Carstairs Junction in conjunction with East Coast Main Line electrification) In 2003, the Crewe– section of the Crewe–Derby line was electrified as a diversionary route for the WCML. Since 1999, the line has been modernised and the overhead line equipment has been refurbished and renewed from Mark 1 / Mark 3A to UK1 range to allow an increase line speeds from 110mph to 125mph (with 140mph capability in areas previously fitted with Automatically Tensioned Mark 1 equipment - subject to upgrading of the balance weight arrangement to provide individually tensioned contact / catenary wires and regrading of the contact wires). At the same time sections of the line are being progressively changed to autotransformer system. Midland Main Line Electrified between London St Pancras and in 1983 using the Mark 3B range, and Dock Junction to Moorgate - now cut back to City Thameslink. Electrification from Bedford to and using the UK Master Series (MS125) range is expected by Spring 2021 (MML Phase 1), further extensions to Leicester, Nottingham Trent Junction and Sheffield (via Derby) by 2023 (MML Phase 2) were cancelled in July 2017. In November 2021, the Integrated Rail Plan (IRP) was published. This included full Midland Main Line electrification. On 21 December 2021 it was announced that work would start immediately on electrification of the section between Kettering and Market Harborough. Grant Shapps claimed this work was proof the IRP was being implemented quickly but was met with ridicule. High Speed 1 Newest main line, completed in 2007. Links London St Pancras with and the Channel Tunnel. East Coast Main Line Electrified in two parts: 1975–78, and 1984–91 The line between and was electrified between 1976 and 1978 using the Mark 3A range as part of the Great Northern Suburban Electrification Project. This included the Hertford loop line. The section between and was electrified in 1988 using the Mark 3B range. In 1984, authority was given to electrify to Edinburgh and . The section between Hitchin and was completed in 1987, and and were reached in 1989.