The most junior Ministers are Parliamentary Under Secretaries of State, of whom there will be one in a small department and three or four in a large department. (The word 'junior' is shorthand used across Whitehall, but that does not mean that they are not significant figures in their department.) They do a great deal of important work, including piloting Bills through Parliament. They also carry out a wide range of representational and other duties, which means that they are always getting up early in the morning to attend events outside London, and then staying in the House until late in the evening to speak in adjournment debates. They take important decisions on individual cases and narrow issues. But they seldom get to take politically important decisions. These are reserved for their seniors.
The second tier of Ministers are Ministers of State, of which there are, again, usually one to three in a department. These Ministers are more experienced and powerful, and will handle – or assist Cabinet Ministers with – the more complex and/or politically tricky issues.
Then there are Cabinet Ministers. Most of them are Ministers in charge of departments, but there are others, including the Leader of the House of Lords and the Chief Whip. Very large or important departments also sometimes get a second Minister in the Cabinet. The Chief Secretary, for instance (who negotiates Government expenditure with his or her colleagues) is number two in the Treasury.
Cabinet Ministers who are in charge of departments are usually styled ‘Secretary of State’ except, for instance, for the Chancellor of the Exchequer. The title of the Secretary of State for the Home Department is almost always shortened to ‘Home Secretary’, and ‘Foreign Secretary’ is also a shortened form. These men and women are of course very powerful, but there is a pecking order within the Cabinet which varies with the political importance of the Minister’s department, and his or her personal clout and experience. But the Chancellor, the Home Secretary and the Foreign Secretary are always very influential, and invariably the top three posts in the pecking order, often out-ranking any Deputy Prime Minister - see below.
The whole structure is headed by the Prime Minister, and sometimes also a Deputy Prime Minister, an analysis of whose role and responsibilities is beyond the scope of this website. Suffice it to say that Prime Ministers have only a limited amount of political capital at their disposal, so they prefer to work through consensus, especially when dealing with senior and powerful colleagues. And as civil servants develop a natural loyalty to their departmental Ministers, the result is that there is no clear pyramid of management responsibility within the civil service, which can make it difficult to handle cross-departmental issues. This issue bedevils various attempts at civil service reform. However, the strengthening of the Cabinet Office, and increased staffing in No.10 have in recent years gone some way towards addressing this problem.