Question: How many miles long is this major railway link between London and Edinburgh, in which The Swinton-Doncaster line is a short railway between Swinton Junction and Doncaster South Yorkshire?

full_context: Document 1: Denaby and Conisbrough railway station: Denaby and Conisbrough railway station was a small station, the southern terminus of the South Yorkshire Junction Railway branch from Wrangbrook Junction. The station, built to serve Denaby Main and Conisbrough, near Doncaster, South Yorkshire, England, was situated just to the north of the Mexborough to Doncaster line of the Manchester, Sheffield and Lincolnshire Railway, close by the road linking the villages in its name. Access to the station was by a subway under the G.C. line.
Document 2: Great Northern Route: The Great Northern Route (formerly known as Great Northern Electrics) is the name given to suburban rail services run on the southern end of Britain's East Coast Main Line and its associated branches. Services operate to or from London King's Cross and Moorgate in London. Destinations include Hertford North , Welwyn Garden City , Stevenage , Peterborough , Cambridge and King's Lynn . Services run through parts of Greater London, Hertfordshire, Bedfordshire, Cambridgeshire and Norfolk.
Document 3: Liverpool–Manchester lines: There were once four direct railway routes between Liverpool and Manchester in the North West of England. There are now only two remaining direct railway routes between the two cities. One line, the now northern route, is fully electric and the other, the southern route, is a diesel only line. A third line which is further north has been split with the western section electric and the eastern section diesel operation, requiring a passenger change between the two cities. The fourth route, the most southerly, is largely abandoned east of Warrington with the remaining section mostly catering for freight trains. The remaining two direct routes are:
Document 4: East Coast Main Line: The East Coast Main Line (ECML) is a 393 mi major railway link between London and Edinburgh via Peterborough, Doncaster, Wakefield, Leeds, York, Darlington and Newcastle, electrified along the whole route. Services north of Edinburgh to Aberdeen and Inverness use diesel trains. The main franchise on the line is operated by Virgin Trains East Coast.
Document 5: Northern City Line: The Northern City Line is a branch railway and commuter line in England, which runs from Moorgate to Finsbury Park in London with services running beyond. It is part of the Great Northern Route services and operates as the south-eastern branch of the East Coast Main Line (ECML). It is underground from Moorgate to Drayton Park in Highbury from which point it runs in a cutting until joining the ECML south of Finsbury Park. Its stations span northern inner districts of Greater London southwards to the City of London, the UK's main financial centre. Since December 2015 the service timetable has been extended to run into the late evenings and at weekends, meeting a new franchise commitment for a minimum of 6 trains per hour until 23:59 on weekdays and 4 trains per hour at weekends.
Document 6: Swinton (South Yorkshire) railway station: Swinton railway station is a railway station in Swinton, South Yorkshire, England. It has three platforms and a small bus station, and lies at the junction of the former North Midland Railway main line between Rotherham Masborough and Leeds via Cudworth and the former South Yorkshire Railway line to Doncaster.
Document 7: Virgin Trains East Coast: Virgin Trains East Coast is a train operating company in the United Kingdom that operates the InterCity East Coast franchise on the East Coast Main Line between London, Yorkshire, the North East and Scotland. It commenced operations on 1 March 2015, taking over from East Coast. It is a joint venture between Stagecoach (90%) and Virgin Group (10%).
Document 8: Sheffield–Lincoln line: The Sheffield–Lincoln line is a railway line in England. It runs from Sheffield east to Lincoln via Worksop, Retford and Gainsborough Lea Road. The route comprises the main line of the former Manchester, Sheffield and Lincolnshire Railway, to Gainsborough, Trent Junction, where it then follows the former Great Northern and Great Eastern Joint Line to Lincoln Central. The former main line continues from Trent Junction to Wrawby Junction, Barnetby, much of it now single line, where it then runs to Cleethorpes. This is currently served by six trains (three each way) on Saturdays only.
Document 9: Dore and Totley railway station: Dore and Totley railway station (named Dore railway station from 1971 until 2008) is a small, one platform railway halt near the Sheffield suburbs of Dore and Totley in South Yorkshire, England 4+3/4 mi south of . The station is served by the Northern service between Sheffield and Manchester, East Midlands Trains service from Liverpool to Norwich and the TransPennine Express service between Manchester and Cleethorpes, all three running via the Hope Valley Line.
Document 10: Swinton–Doncaster line: The Swinton–Doncaster line is a short railway line in South Yorkshire between Swinton Junction on the Wakefield Line and Doncaster South Yorkshire Junction on the East Coast Main Line. The line comprises the former North Midland Railway's "Swinton curve" between Swinton and Mexborough and the east end of the former South Yorkshire Railway Blackburn Valley line, between Mexborough and Doncaster. Northern operates passenger trains on the line; TransPennine Express and CrossCountry use the line but do not provide stopping service.
Document 11: Swinton Central railway station: Swinton, later Swinton Central railway station was situated on the South Yorkshire Railway line from Sheffield Victoria to Doncaster, between Kilnhurst Central and Mexborough. The station was to serve the community of Swinton Bridge, near Mexborough, South Yorkshire, England.
Document 12: West Coast Main Line: The West Coast Main Line (WCML) is one of the most important railway corridors in the United Kingdom, connecting the major cities of London, Birmingham, Glasgow, Liverpool and Manchester. It is one of the busiest mixed-traffic railway routes in Europe, carrying a mixture of intercity rail, regional rail, commuter rail and rail freight traffic. The core route of the WCML runs from London to Glasgow, with branches diverging to Birmingham, Manchester and Liverpool, totalling a route mileage of 700 mi . Services from London to North Wales and Edinburgh also run via the WCML; however the main London-Edinburgh route is the East Coast Main Line. In addition, several sections of the WCML form part of the suburban railway systems in London, Birmingham, Manchester and Glasgow, with many more smaller commuter stations, as well as providing links to more rural towns.
Document 13: Doncaster railway station: Doncaster railway station serves the town of Doncaster, in South Yorkshire, England. It is situated on the East Coast Main Line 156 mi north of London King's Cross and managed by Virgin Trains East Coast. It is a major passenger interchange between the East Coast Main Line and Cross Country Route and local services running across the North of England. It is also the point for which Virgin Trains East Coast services from London divide, either branching off to Leeds or continuing north to Scotland via Newcastle and the North East.
Document 14: Midland Mainline: Midland Mainline was a train operating company in the United Kingdom owned by National Express that operated the Midland Main Line franchise from April 1996 until November 2007. Midland Mainline ran fast and semi-fast passenger services from London to the East Midlands and Yorkshire, on the Midland Main Line. Most services ran between London St Pancras and either Derby, Nottingham or Sheffield. Some services extended to Burton upon Trent, Matlock, Barnsley, Leeds, York and Scarborough.
Document 15: East Coast (train operating company): East Coast was a British train operating company that operated the InterCity East Coast franchise on the East Coast Main Line between London, Yorkshire, the North East and Scotland. East Coast operated long distance inter-city services from its Central London terminus at on two primary routes; the first to Leeds and the second to Edinburgh via Newcastle with other services reaching into Yorkshire and Northern and Central Scotland. It commenced operations on 14 November 2009 and ceased on 28 February 2015.
ground_truth: 393 mi