The Cabinet is the ultimate decision-making body of the executive within the Westminster system of government in traditional constitutional theory. This interpretation was originally put across in the work of 19th century constitutionalists such as Walter Bagehot, who described the Cabinet as the "efficient secret" of the British political system in his book "The English Constitution". The political and decision-making authority of the cabinet has been gradually reduced over the last several decades, with some claiming its role has been usurped by a "prime ministerial" government. In the modern political era, the prime minister releases information concerning Cabinet rank in the form of a list detailing the seniority of all Cabinet ministers.