[6] The line at Derby was joined on 1 July 1840 by the North Midland Railway to Leeds Hunslet Lane via Chesterfield, Rotherham Masborough,[n 1] Swinton, and Normanton.

There are also major summits at Kibworth, Desbrough and at Sharnbrook where a 1 in 119 gradient from the south over 3 miles (4.8 km) takes the line to 340 feet (104 m) above sea level.

James Allport arranged a seven-year deal with the GN to run into Kings Cross for a guaranteed £20,000 a year (equivalent to £2,410,000 in 2023).

The mid-1870s, saw the Midland line extended northwards through the Yorkshire Dales and Eden Valley on what is now called the Settle–Carlisle Railway.

Most Leicester-Nottingham local passenger trains were taken over by diesel units from 14 April 1958, taking about 51 minutes between the two cities.

The Beeching cuts and electrification of the West Coast Main Line brought an end to the marginally longer London–Manchester service via Sheffield.

In 1977, the Parliamentary Select Committee on Nationalised Industries recommended considering electrification of more of Britain's rail network, and by 1979 BR presented a range of options that included electrifying the Midland Main Line from London to Yorkshire by 2000.

[16] By 1983, the line had been electrified from Moorgate to Bedford, but proposals to continue electrification to Nottingham and Sheffield were not implemented.

Improved signalling, increased number of tracks, and the revival of proposals to extend electrification from Bedford to Sheffield are underway.

Traffic levels on the Midland Main Line are rising faster than the national average, with continued increases predicted.

[21][22][23][24] After electrification, the North Northamptonshire towns (Wellingborough, Kettering, and Corby) are planned to have an additional 'Outer Suburban service' into London St Pancras, similar to the West Midlands Trains' Crewe – London Euston services, to cater for the growing commuter market.

[26][27] Highlights include:[28] The Thameslink Programme has lengthened the platforms at most stations south of Bedford to 12-car capability.

St Pancras, Cricklewood, Hendon, and Luton Airport Parkway were already long enough, but bridges at Kentish Town mean it cannot expand beyond the current 8-car platform length.

These included a commitment to complete the stalled electrification work, an upgrade to digital signalling, and a connection to High Speed 2.

This will allow HS2 services to connect to both Derby and Nottingham city centres directly using the MML for access, which was a criticism of the previous HS2 eastern leg proposal.

This line was closed in the 1960s between Matlock and Buxton, severing an important link between Manchester and the East Midlands, which has never been satisfactorily replaced by any mode of transport.

A section of the route remains in the hands of the Peak Rail preservation group, operating between Matlock and Rowsley to the north.

World War I prevented the Midland Railway from finishing its direct route through the West Riding to join the Settle and Carlisle (which would have cut six miles from the journey and avoided the need for reversal at Leeds).

Closing it today would also need to take into account the different levels between the two Bradford stations, a task made easier in the days of electric rather than steam traction, allowing for steeper gradients than possible at the time of the Midland's proposed extension.

The line served two goods stations and provided a route for occasional express passenger trains before its eventual closure in 1968.

The failure to complete this section ended the Midland's hopes of being a serious competitor on routes to Scotland and finally put beyond all doubt that Leeds, not Bradford, would be the West Riding's principal city.

Midland trains to Scotland therefore continued to call at Leeds before travelling along the Aire Valley to the Settle and Carlisle.