First MTR South Western Trains Limited, trading as South Western Railway (SWR), is a British train operating company owned by FirstGroup (70%) and MTR Corporation (30%) that operates the South Western franchise. It operates commuter services from its Central London terminus at London Waterloo to South West London. SWR provides suburban services in the counties of Surrey, Hampshire and Dorset, as well as regional services in Devon, Somerset, Berkshire and Wiltshire. Its subsidiary Island Line operates services on the Isle of Wight.

SWR was awarded the South Western franchise in March 2017, and took over from South West Trains on 20 August 2017.

South Western Railway Mainline Services

South Western Railway operates regular services on four mainline routes:

The South West Main Line (SWML) runs between London (Waterloo station) and the town of Weymouth; the route passes through several large towns and cities, including Woking, Basingstoke, Winchester, Southampton, Bournemouth, Poole and Dorchester. South Western Railway operates trains along the entire length of the line. Almost all trains operated by the company start from or terminate at London Waterloo; these include stopping services as far as Basingstoke, semi-fast services to/from Southampton and Poole, and express services to/from Weymouth. There are also trains to and from Portsmouth; these trains branch off the SWML at Eastleigh, then proceed via the Eastleigh to Fareham and West Coastway lines to Portsmouth Harbour station. In addition to the South Western Railway services, CrossCountry operates regular passenger services on the line between Basingstoke, Southampton and Bournemouth; these usually run to and from Manchester or Newcastle.

The Portsmouth Direct Line (PDL) branches off the SWML at Woking and runs to Portsmouth via Guildford, Haslemere, Petersfield and Havant. South Western Railway operates all passenger trains on this route; these include fast and semi-fast services between London and Portsmouth, and semi-fast services as far as Haslemere.

The West of England Main Line (WEML) is the only mainline route that is not fully electrified. It leaves the SWML at Basingstoke and runs to Exeter via Andover, Salisbury, Gillingham and Yeovil. South Western Railway is the only operator on the line, with most services running between London and either Salisbury or Exeter St Davids. Some peak-time services terminate at various other destinations on the line, including Gillingham and Andover; other peak services branch off the line and run to Bristol Temple Meads station via the Wessex Main Line. On Summer Saturdays, there is also a daily return service to Weymouth, which leaves the WEML at Yeovil Junction and continues via the Heart of Wessex Line.
The Alton Line leaves the SWML at Brookwood (just after Woking) and runs to Alton via Aldershot and Farnham. It is the shortest of the four mainline routes and as such, it is sometimes considered an outer suburban route instead (however for ticketing purposes, it is classed as a mainline route). Services usually run the full length of the line between London and Alton, though some services terminate at Farnham.

In total, there are 14 mainline trains per hour departing London Waterloo in the off-peak; this number increases in the peak hours. The majority of mainline services are operated by Class 444 or Class 450 EMUs, except for the West of England Main Line which is always operated by Class 158 or Class 159 DMUs (because it is unelectrified) and the Alton Line which also sees the occasional use of Class 458 units.