The railway network in Great Britain consists of approximately 10,000 miles of track and serves around 2,500 stations. The railway infrastructure is owned and operated by Network Rail while passenger services and all but 17 stations are operated by a total of 26 privately owned train operating companies (Network Rail directly operate the remaining 17 principal stations). The Irish network is naturally much smaller, with just 300 miles of track in Northern Ireland and around 1,400 miles of track in the Republic of Ireland, less than half of the original total of 3,600 miles of track. There are also 1,200 miles of private 3 ft (914 mm) gauge narrow gauge railways used for transporting peat by Bord na Móna, a company of the Irish government.
In 2005/2006 there were over 1 billion passenger journeys in Great Britain, the largest number since 1959, and during 2005/6 Network Rail will have spent approximately £5.1 billion on the routine maintenance and upgrading of the network. Network Rail continues to spend the equivalent of £14 million every day on maintenance and upgrading of the network.
In Ireland, the rail network has arguably suffered from much more serious under-investment than its mainland counterpart and passenger numbers are often negligible on some routes, however the two railway companies on the island have recently spent considerable sums upgrading track and rolling stock.
The City and South London Railway (C&SLR) was the first deep-level underground "tube" railway in the world, and the first major railway in the world to use electric traction. Originally intended for cable-hauled trains, the collapse of the cable contractor while the railway was under construction forced a change to electric traction before the line opened – an experimental technology at the time.
When opened in 1890, it served six stations and ran for a distance of 5.1 kilometres (3.2 mi) in a pair of tunnels between the City of London and Stockwell, passing under the River Thames. The diameter of the tunnels restricted the size of the trains and the small carriages with their high-backed seating were nicknamed padded cells. The railway was extended several times north and south; eventually serving 22 stations over a distance of 21.7 km (13.5 mi) from Camden Town in north London to Morden in Surrey.