The Ringwood, Christchurch and Bournemouth Railway was a railway company to link Christchurch and Bournemouth to the London and South Western Railway's Southampton and Dorchester line at Ringwood. The RC&BR opened in 1862 from Christchurch to Ringwood, and was extended to Bournemouth in 1870, sharing in the growing popularity of the town. However the route was circuitous, and the London and South Western Railway opened a shorter route between Brockenhurst and Christchurch via Sway in 1888, making the Ringwood to Christchurch section a branch line.
A feature of the line was that a landowner had the right to stop any train at a private station, a fact that became an embarrassment when express trains started to operate.
The section from Ringwood to Christchurch closed in 1935, but the Christchurch to Bournemouth section remains as part of the South Western Main Line.
The London and South Western Railway (LSWR) reached Southampton in 1840, and independent interests promoted the Southampton and Dorchester Railway to connect Dorchester to London. The line was built, opening in 1847, but its route took it on a northerly alignment from Brockenhurst through Ringwood and Wimborne. The line was leased to, and worked by the LSWR, and later absorbed by it. Bournemouth was not an important settlement at the time, and was left some distance from the line; it had a population in 1851 of only 1,330. There was a branch serving Poole, but that was located on the south side of the Holes Bay inlet.
In the following decade, Bournemouth grew in importance and it became desirable to provide a railway connection. After a failed attempt, local interests promoted the Ringwood, Christchurch and Bournemouth Railway, a 7 3⁄4-mile (12.5 km) line from the northern margin of Christchurch to the Southampton and Dorchester line near Ringwood. As originally designed, the junction there would have faced west, towards Wimborne. The route followed the valley of the River Avon. The engineer was Captain William Moorsom.
Early LSWR opposition having been withdrawn, the railway obtained its authorising Act of Parliament on 8 August 1859, with capital of £45,000. The contractor was Thomas Brassey and the line was quickly constructed; the west facing junction at Ringwood was changed to face towards Southampton, the new line running alongside the double track of the Southampton and Dorchester line for some distance, joining it at Ringwood station. It was a single line, with sharp curves and difficult gradients.