Nationalisation of the railways, along with the canals and major bus operators, was a clear commitment in the Labour Party Election Manifesto of 1945 and came about from 1st January 1948. A complex structure under the British Transport Commission was put in place to manage the vast organisation, with an Executive responsible for each main mode of transport.

In Cumbria this meant that the railways were allocated more or less as previously organised to the new London Midland (LMS) and Eastern Regions (LNER), but with all lines of both companies in Scotland coming under the Scottish Region. Initially this meant that the Silloth branch was in the Scottish Region, but was quickly transferred within months to the Eastern, then the London Midland. Regional boundaries were set at Gretna on the former Caley line and Harker on the NB. This left Kingmoor locoshed still in the Scottish Region as 68A until 1958, with Canal as a sub-shed for much of this time. A couple of years later further "rationalisation" saw the NER Stainmore lines in Cumbria transferred from the North Eastern to the London Midland Region.

During the early years of nationalisation the daily scene carried on much as before but first with "BRITISH RAILWAYS" appearing on loco tender and tank sides, then the famous "wheeling lion". At last the almost universal wartime black locomotive livery was relieved by the short-lived Caley blue on express engines, and then the rich Brunswick green.

Of great excitement to enthusiasts in 1948 was the so-called "Locomotive Exchanges" during which engines from the "Big Four" companies were trialled over a variety of lines across the country, supposedly so that their best features could be identified before a new series of steam locomotives was constructed to a set of standard designs. For a few weeks exotic classes appeared on West Coast express workings including SR Bulleid Merchant Navy and LNER Gresley A4 Pacifics but unfortunately the GWR Kings could not be cleared to work on the West Coast line.

However, the first signs of any new investment were rare. From 1948 Ivatt's new express diesel locos would appear from time to time at Carlisle on expresses to or from London, and there had been a small group of LMS 0-6-0 shunting locos in Carlisle for some time. But it was not until January 1955, literally weeks before the publication of British Railways Modernisation Plan, that the first of the new Derby lightweight diesel multiple units appeared on services in West Cumberland. These revolutionised services and attracted many new passengers. On the main line it was 1960 before new main line diesels started to appear in numbers and the impending end of steam haulage became obvious.

Growing financial deficits on the railway by this time were forcing the government to examine ways of making the railways more efficient. Many closures of stations had taken place during the 1950s, and of some passenger services, including the Coniston Branch, but with the appointment of Dr Richard Beeching as chairman of the new British Railways Board in 1961, and the publication of his "Reshaping of British Railways" report on 1963 laid the path for many more lines and stations to close during the mid-1960s. The Stainmore lines had already closed in 1962, but those now to go included the Silloth and Langholm branches (1964), Lakeside (1965), Morecambe to Wennington (1966), Workington to Penrith (1966/1972), Waverley line (1969), Settle & Carlisle local stations (1970) and the Alston branch (1972).

Government commitment to electrifying the West Coast line was made in 1959 but for the section northwards to Scotland this was not forthcoming until much later, and the job was completed in 1974. This completed revolution in long-distance train services which had begun in 1966, and resulting in regular interval services all day between London and Glasgow with a massive increase in passenger carryings following in train.

Closure of the Settle & Carlisle line was mooted in the early 1970s on completion of the WCML electrification, it providing an essential diversionary route during these works. However, the continued use of loose-coupled non-braked wagons was incompatible with the high speed more intensive timetable and the S&C survived. As this traffic declined to nothing, and with the withdrawal or diversion of long-distance passenger services leaving only a twice daily local service, the route was proposed for closure in 1984. A massive outcry of objection resulted and after a five-year battle the line was reprieved by Minister Michael Portillo with a challenge to make it work for its living. Local services had already been re-introduced and passenger numbers increased more than sixfold. Judicial planning permissions ensured that freight traffic re-commenced, and in more recent years this has expanded almost to line capacity after the closure of pits in the Yorkshire coalfield, coal for the associated power stations now being imported via Hunterston on the Clyde. Much more has also been done to enhance the line and its stations.

The continued decline of the traditional heavy industries of coal and steel continued, especially from the mid-1960s with the closure of major coal mines at Great Clifton (1959), Walkill at Moresby 1961), Risehow at Flimby and St.Helens at Siddick (1966), Harrington No.10 at Lowca (1968), Solway at Workington (1973) and finally Haig at Whitehaven in 1983. Even open-cast coal, which had latterly been railed to power stations in Lancashire and the Midlands from a new terminal at Maryport, came to an end in 1993. Bessemer steel making at Workington ended in 1975 followed by the blowing out of the blast furnaces in 1982 but the rolling of rails was to continue until 2007; quarries and iron ore mines also closed, the last of the latter in 1982. For the railways this meant a final contraction of remaining inland lines, leaving little more than just the coastal route ‐ and little freight other than that generated by the nuclear establishment at Sellafield.

During the period after Beeching the railways went through several more changes in organisation at local level. The structure of Regions was to last until the early 1990s, but within the London Midland Region a structure of geographical Divisions was set up in the 1960s with Areas under them. Barrow Division managed all the whole Cumbria area with area managers located at Carlisle, Workington, Lancaster and Skipton. Barrow Division, however, was fairly short-lived and Cumbria then came under Preston and, finally, Manchester. At the same time Areas grew so that by the 1980s Carlisle Area was almost co-terminous with the earlier Barrow Division. Re-organisation on a business basis swept all this away, with each business responsible for its own rolling stock and infrastructure (where it was the principal user). In Cumbria this meant the West Coast main line and stations coming under InterCity West Coast, and all other lines in the Regional Railways organisation, lines west of the WCML being in RR North East, those to the west in RR North West. OfQ or Organising for Quality, as this was entitled was the last, and very successful structure of British Railways before privatisation was progressively implemented from the mid-1990s.

For further reading see Bibliography