Network Rail is the owner (via its subsidiary Network Rail Infrastructure Ltd which was known as Railtrack plc before 2003) and infrastructure manager of most of the rail network in England, Scotland and Wales,
Network Rail is a 'not for dividend' company limited by guarantee with no shareholders which applies its income to its own purposes. The Secretary of State for Transport is a 'Special Member' of the company's board of management and possesses additional powers over other members. Network Rail's main customers are the separate and mostly private train operating companies (TOCs), responsible for passenger transport, and freight operating companies (FOCs), who provide train services on the infrastructure that the company owns and maintains.
Since 1 September 2014, Network Rail has been classified as a "public sector body".
To cope with quickly rising passenger numbers, Network Rail is currently undertaking a £38 billion programme of upgrades to the network, including Crossrail, electrification of lines, upgrading Thameslink and a new high-speed line. (Source: Wikipedia)