Train Portsmouth - Hatfield, Hertfordshire prices from CHF 14.69

Great Western Railway (GWR) is a British railway company that operates passenger services between London and the southwest of England, as well as parts of Wales. It was founded in 1833 and was originally known as the Great Western Railway Company. GWR is now owned by FirstGroup. The company is known for its iconic green livery and its historic steam locomotives, including the famous Flying Scotsman.

London Overground is a suburban rail network in London, England. It was created in 2007 by the merger of the former Silverlink Metro service with other rail services. The network consists of 112 stations and serves 23 London boroughs. London Overground operates on these routes, which include Highbury & Islington to West Croydon/Clapham Junction/Crystal Palace, Richmond/Clapham Junction to Stratford, Gospel Oak to Barking Riverside, Watford Junction to Euston, Liverpool Street to Enfield Town/Cheshunt, Liverpool Street to Chingford, and Romford to Upminster. Overground is operated by Arriva Rail London under a concession from Transport for London.

South Western Railway (SWR) is a train operating company in the United Kingdom that operates passenger services in South West England and parts of Southern England. It was formed in 2017 as a result of the merger of South West Trains and the Island Line Trains. SWR operates services to major cities such as London, Bristol, Southampton, and Portsmouth, as well as smaller towns and villages in the region. The company operates a fleet of modern trains, including electric and diesel multiple units, and provides a range of ticketing options, including season tickets, advance purchase tickets, and flexible fares. SWR is owned by FirstGroup and MTR Corporation.

Thameslink is a railway service in the United Kingdom that runs through central London, connecting Bedford in the north and Brighton in the south. It is operated by Govia Thameslink Railway and serves over 200 stations, including major transport hubs such as St Pancras International, London Bridge, and Gatwick Airport. Thameslink trains run every few minutes during peak hours and offer a range of services, from fast express trains to stopping services that serve local communities. The service has undergone significant upgrades in recent years, including the introduction of new trains and the completion of major infrastructure projects such as the Thameslink Programme.

National Rail is a network of railway companies that operate in England, Scotland, and Wales. It encompasses a network of train operators, including Train Operating Companies, open access operators, freight operating companies, and Network Rail. National Rail is managed and supported by the Rail Delivery Group (RDG), which provides essential business services to ensure the smooth operation and coordination of the railway industry.