You will not find much about what the Prime Minister does in the text-books. What he does is partly made up of convention and custom, but the nature of the office depends a great deal on the person who holds it. ... Make it [the Cabinet] as small as possible. Democracy means government by discussion, but it is only effective if you can stop people talking. Some of my early Cabinets were very small, but I arrived at the conclusion that 16 is the right number.