The Didcot, Newbury and Southampton Railway (DN&SR) was a cross-country railway running north–south between Didcot, Newbury and Winchester. Its promoters intended an independent route to Southampton and envisaged heavy traffic from the Midlands and North of England to the port, but they ran out of funds to complete the line to Southampton. The intended heavy through traffic never materialised, and the line was dependent on larger railways—the Great Western Railway and the London and South Western Railway—for support, which was not freely given. The line opened in two stages, in 1882 and 1885.
The Company was absorbed by the Great Western Railway in 1923 following the Railways Act 1921. It became strategically important during World War II when huge volumes of munitions and troops were transported to South Coast ports, particularly in the preparations for the Normandy landings, and the Didcot to Newbury section was doubled, while the southern section was upgraded with extended passing loops.
The line never carried heavy passenger volumes and declining traffic led to its closure in stages from 1960 to 1964.