
Nationalisation and Modernisation
The Transport Act in 1947 set the way for the rail network in Great Britain to become a nationalised organisation as part of a policy for nationalising public services. On 1st January 1948 the "Big Four" railway companies in the UK merged and British Railways was created. (Before this point the existing railway companies were already effectively bankrupt.)
The Stour Valley lines as well as the other southern lines from LNER became part of the BR Eastern Region.

During the war years the British railway network had become very run down and in desperate need of major investment of new trains and new infrastructure. Other countries at this time had already begun replacing their steam trains with modern diesels or electrics, but Britain were still using the old steam engines, and the network was rebuilt slowly which allowed it to deteriorate even more.
In 1955 the British Transport Commission released their plan to modernise and re-equip British Railways, this involved the suggestion to electrify principal routes, replace steam engines with new diesel and electric locomotives, along with new coaching stock. Also widespread track replacement and re-signalling was planned.
The plan failed to take account of the effect that road transport would have on rail, and large sums of money were wasted, many of the new locomotives were not properly tested and scrapped after only a few years of use.
During this period on the Stour Valley Line, life continued pretty much as normal with the added bonus of the long distance express services which would pass though during the summer of 1954 taking passengers between Leicester and Clacton on Sea via Cambridge and Sudbury, as well as the service between Sheffield and Clacton via Bury St Edmunds and Sudbury.
On January 1st 1959 the biggest change happened - the steam engines were withdrawn and diesel multiple units (DMUs) and Diesel Railcars took over the passenger services on the Stour and Colne Valley Railways. This allowed considerable cuts to the made in the cost of operation, however it wasn't enough to save most of the route.
The Beeching Cuts ---->
History