The Portsmouth line is a secondary main line originally built by the London, Brighton and South Coast Railway and the London and South Western Railway between 1847 and 1868. It leaves the South London Line (Atlantic Lines) at , with connections to the Victoria branch of the Brighton Main Line at , and continues via , and to join the Mid-Sussex LineAlso known as the "Arun Valley Line", although that name is sometimes used only for the section from Horsham to Arundel, the actual Arun valley. at .
As of 2022, the line is predominantly a commuter line and there are no scheduled services running along the entire route. The current service pattern can be divided into three sections. The first of these runs from Peckham Rye to Streatham (Southern), with trains then switching on to the Brighton Main Line towards and ; the second is the Streatham to Sutton section (Thameslink), part of the Sutton Loop Line, and the third runs from Sutton to Horsham (Southern), with trains originating from London Victoria and joining the Portsmouth line south of Streatham.
Names The Portsmouth line refers to the preferred route from London to Portsmouth on the former LB&SCR system, and particularly the cutoff from Peckham Rye to Horsham. It is not generally applied north of Peckham Rye or south of Horsham because those lines have well-known identities established before the Portsmouth connection was completed: the South London Line, the Mid-Sussex Line and the West Coastway Line.
For a time passenger services on the Portsmouth line and some associated branches were timetabled and marketed as the Sutton & Mole Valley Lines. Since 2007 that name no longer appears in Southern or National Rail publications.
The Portsmouth Line should not be confused with the Portsmouth Direct Line (originally called the "Direct Portsmouth Railway"). The Portsmouth Direct, before the Grouping part of the LSWR system,The DPR was built speculatively by the contractor Thomas Brassey then acquired by the LSWR. has been the primary route from London to Portsmouth since it opened. It leaves the South West Main Line at and runs via to . From Havant to it shares the LBSCR route.
From Portcreek Junction to Portsmouth the route was owned and operated jointly by the LBSCR and LSWR, and that section is known as the Portsmouth Joint Line.From 1880 also including a line from to on the Isle of Wight, linked to Portsmouth Harbour by a ferry service.
History Early railways to Portsmouth were far from direct. In 1841 the LSWR opened a branch from (on the London-Southampton main line) to , with a ferry across the harbour to Portsmouth. By 1847 the LBSCR had extended its West Coastway Line from to Portsmouth Town, with trains from , and from with a reversal (or change) at Brighton.The Cliftonville Curve, which allows direct access from the Brighton Main Line to the West Coastway at Hove, was not opened until 1879. In 1848 the LSWR opened a branch from on the Gosport line to join the LBSCR at Portcreek Junction, and negotiated with the LBSCR for joint ownership of the line to the Portsmouth terminus. Surprisingly over such a distance the two routes from London were almost identical in length, the Brighton route being shorter by just 51 chains (94m 43ch from London Bridge via Brighton, vs. 95m 14ch from Waterloo via Eastleigh).From Waterloo only after 10 October 1848. For the 3 months from the opening of the Fareham-Cosham line until the Nine Elms-Waterloo viaduct opened the LSWR route had been shorter by 1m19ch (93m 75ch from Nine Elms).
For a decade these remained the only lines into Portsmouth. The people of Portsmouth and particularly the Admiralty thought such roundabout routes were unsatisfactory for a major naval base, especially when the rival port of Southampton, and Brighton, a mere seaside resort, were served by fast direct lines from London. Various schemes were proposed for shorter lines, including routes via Horsham and via the Wey Valley. The eventual winner was the Direct Portsmouth Railway, authorised in 1853 and opened in 1858. This extended the LSWR Godalming branch to meet the LBSCR West Coastway at Havant. It was operated and later acquired by the LSWR, and quickly became the most popular route to Portsmouth, despite initial obstructive tactics by the LBSCR at Havant.
This put the LBSCR at a disadvantage, but over the following decade they developed a number of lines in Surrey and West Sussex that substantially improved their Portsmouth service.
Thus the route that eventually became the Portsmouth Line was built in stages over an extended period:
Along The North Downs Arrival at Epsom Sutton and Epsom were first reached by an extension of the London and Croydon Railway (L&CR) from West Croydon. This was promoted by the L&CR as an independent company, the Croydon and Epsom Railway (C&ER), and was originally proposed to be an atmospheric railway.
In 1846 the C&ER merged with the L&CR, the London & Brighton Railway and others to form the LBSCR, and in 1847 the Croydon and Epsom route was completed as a conventional locomotive-hauled line under LBSCR auspices. It ran via Wallington, Sutton, Cheam and Ewell to an Epsom station on the east side of town.
Extending to Leatherhead Twelve years later the independent Epsom and Leatherhead Railway (ELR) built a line from a new station on the west side of Epsom to Leatherhead, opening in February 1859 as a single line with just one intermediate station, at Ashtead. The LSWR-promoted Wimbledon and Dorking Railway connected end-on at Epsom, opening in April 1859. On 8 Aug 1859 the LBSCR opened an extension from its existing Epsom station to the ELR. Within a year the ELR was jointly acquired by the LSWR and LBSCR.
Avoiding Brighton Horsham and The Arun Valley A single-line branch from the Brighton Main Line at Three Bridges to Horsham, later known as the Mid-Sussex Line, had opened in 1848. It was extended down the Arun Valley to Petworth via Pulborough in 1859 (eventually reaching Midhurst in 1866). In 1862 it was doubled throughout, and the following year it was extended from Hardham Junction, south of Pulborough, to Arundel Junction on the West Coastway Line. This, in 1863, gave the LBSCR a more direct path from London to Chichester and Portsmouth than the long detour via Brighton, although it followed two-thirds of the Brighton Main Line before turning cross-country.
The Mole Valley: Leatherhead to Horsham In 1862 the Horsham, Dorking and Leatherhead Railway (HDLR) was authorised to provide a link from the Mid-Sussex Line at Horsham to Leatherhead, crossing the North Downs via the Mole Valley between Dorking and Leatherhead. The line connected to the ELR just east of the existing Leatherhead station, which became a terminus used by LSWR services only. The HDLR provided a new through station just across the road, the one still in use today. At Dorking there was a south-to-west spur to the South Eastern Railway's Reading, Guildford and Reigate Railway, but this was never used for regular services.
When the HDLR opened in 1867 it created an LBSCR route to Portsmouth that avoided much of the busy Brighton Main Line, although it was actually longer than the Mid-Sussex/Arun Valley route,88m 31ch from Victoria to Portsmouth Town via West Croydon and Sutton, against 85m 45ch via Three Bridges and still used the congested lines through and .
The Sutton cutoff So far the LBSCR route to Epsom and beyond had been via the Wallington (West Croydon to Sutton) line but in 1868, only a year after the Horsham to Leatherhead connection, they opened a line from Peckham Rye to Sutton via and . Although it primarily filled gaps in the LBSCR suburban network it also improved the route to Portsmouth, being slightly shorter than via Wallington,Victoria to Portsmouth Town was now 85m 26ch, the shortest ever route on the LBSCR, but still far longer than the Portsmouth Direct at 73m 38ch from Waterloo. and bypassed the bottlenecks at Norwood Junction and Selhurst; so it was promoted as a new "Portsmouth Line".
Contemporary maps label it the "South London & Sutton Junction Railway" suggesting that, as with other sections of the Portsmouth Line, this part may initially have been vested in an independent company to insulate the LBSCR from financial problems; although there is no evidence that they used such a vehicle for either construction or operation of the line.
Connections
On opening in 1868 the Sutton line had many links, all but one to other LBSCR lines: A branch from the Chatham Main Line (LCDR) at to Tulse Hill Chords from Tulse Hill up to the Crystal Palace Line in both directions The Brighton Main Line junctions at Streatham: a double-track SW to SE chord from Streatham (Streatham Junction) down to the Slow Lines at a double-track flying junction SE to SW from the Slow Lines (Streatham North Junction) to the Portsmouth (Streatham South Junction) a separate single-track chord with crossovers up from the Fast Lines The Wimbledon Loop branching off west at Streatham South Junction Crossing the Wimbledon and Croydon Railway at Mitcham Junction, a new station created specifically for this interchange At Sutton the line from West Croydon via Wallington joins in a trailing direction, and the Epsom Downs Branch turns away to the south
Engineering The section from Peckham Rye to Streatham passes through the grounds of Dulwich College and relatively hilly terrain, which required some costly engineering works: A brick-lined cutting leading to station An ornate brick-arch viaduct through the College grounds, with several cast-iron road overbridges Knights Hill Tunnel Leigham Tunnel Streatham Tunnel The arches of the viaduct and the south portal of Knight's Hill Tunnel are adorned with the monogram "AC", in tribute to the landowner Alleyn's College, as Dulwich College was known at the time the line was built.
Mitcham Junction station is approached from both directions by severe curves that turn the Portsmouth Line through 90-degrees to join the alignment of the Wimbledon-Croydon line (running NW-SE), then back to resume its broadly SW alignment.The curves on the Portsmouth Line remain, but in 1997 the Wimbledon-Croydon tracks were converted to a grade-separated tram line, with a flyover crossing the Portsmouth Line south of Mitcham Junction.
Later Connections
In 1885 the LSWR opened the New Guildford Line from to via Cobham. This included a branch from At this stage just a junction in the Guildford direction; Effingham Junction station was not opened until 1888. via to the Portsmouth Line at Leatherhead. This turned the old LSWR terminal at Leatherhead into a through station, and enabled a "Guildford via Epsom" service which continues to this day.
After the Grouping, in 1927 the Southern Railway diverted the Bookham line to join the HDLR to the west of the LBSCR station, which then became the only Leatherhead station. A stump of the original ELR/LSWR line was retained for carriage sidings.
Also in 1927 the Southern Railway completely rebuilt Epsom LSWR station and layout to give the LBSCR (Sutton) line access to the platforms. Epsom Town was closed to passengers in 1929, and became the main goods station for the area, relieving the cramped yard at Epsom (LSWR).
One of the last new lines to be built in Britain before the HS1 era was the Wimbledon and Sutton Railway (W&SR), from Wimbledon through Merton and Morden, to join the Portsmouth Line in the up direction south of Sutton. Construction began in 1927Proposals for the W&SR had been around since 1910, but the Great War and then the Grouping delayed implementation for 17 years. and was completed in 1930. The Wimbledon & Sutton line is now part of a circular route from Streatham, via the Portsmouth Line to Sutton, the W&SR to Wimbledon, then the Wimbledon Loop (northern branch) back to Streatham.
Technical information Tunnels There are five tunnels, built between 1860 and 1867: