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.

Didcot is a railway town and civil parish in South Oxfordshire, England, located 15 miles (24 km) south of Oxford, 10 miles (16 km) east of Wantage and 15 miles (24 km) north west of Reading. Historically part of Berkshire, the town is noted for its railway heritage, Didcot station opening as a junction station on the Great Western Main Line in 1844. Today the town is known for the railway museum and power stations, and is the gateway town to the Science Vale: three large science and technology centres in the surrounding villages of Milton, Culham and Harwell.