 Contracts between the principal passenger train operators and the state are called "franchise agreements", which specify minimum service levels, and the amount of subsidy / premium to be paid over the course of the franchise.Franchises were first the responsibility of the Office of Passenger Rail Franchising, then its successor the Strategic Rail Authority and now with the Secretary of State for Transport.Initially, British Rail was broken up into various units frequently based on its own organisational sectors, still controlled by the British Railways Board, but which were sold off over the next few years.