These powers include the patronage powers to hire, fire and reshuffle. When it comes to hiring the Prime Minister can select ministers to his advantage, choosing those who will make up the cabinet is considered to be one of the most important powers of the Prime Minister. For example, Blair favoured appointing other Blairites, some argue this was to supress the views of Brown. Prime Ministers also have the power to fire ministers for a variety of reasons, such as ministers failing to comply with collective responsibility. Examples include Michael Heseltine and his disagreement with the cabinet over the sale of Westland Helicopters. Prime Ministers could also fire over policy disasters, such as when Edwina Currie claimed in 1983 that the British egg production was contaminated with salmonella.
In the parliamentary system a cabinet reshuffle or shuffle is an informal term for an event that occurs when a head of government rotates or changes the composition of ministers in their cabinet. Cabinet reshuffles happen for a variety of reasons. Periodically, smaller reshuffles are needed to replace ministers who have resigned, retired or died. Reshuffles are also a way for a premier to "refresh" the government, often in the face of poor polling numbers; remove poor performers; and reward supporters and punish others. It is common after elections, even if the party in power is retained, as the prime minister's reading of public opinion as evidenced by the election may require some change in policy, in addition to any changes resulting from the retirement or defeat of individuals ministers at the election. David Cameron reshuffled in 2014, and William Hague, who was foreign secretary, was promoted to leader of the House of Commons.
The Prime Minister also has control over the cabinet agenda and minutes. The Prime Minister chairs the regular Cabinet meetings and sets the agenda for those meetings. During these meetings decisions on implementing government policy will be made. Through the Cabinet Office, which monitors the activities of all the Departments of State, Prime Ministers maintain an overview of how Cabinet decisions are being implemented. For example, Thatcher decided that her agenda would include privatisation of nationalised industries in the 1980s.
Moreover, the Prime Ministers has control over the chairs of cabinet committees. It is the Prime Minister who will establish the committee, give it its term of reference and appoint its chair and members. An official announcement on the number and nature of these committees had to wait until 1992 when John Major finally went public and published details of the whole structure. The committees have both an administrative and political purpose, and the Prime Minister has a good deal of power over both aspects. The majority of decisions taken by the Cabinet are, in effect, taken by cabinet committees.
Finally, the Prime Minister has the ability to by-pass cabinet through “pre-cooking” policy. Prime Ministers have tended, in recent years, to have an 'inner' Cabinet of very close colleagues. On major issues, this group will often have decided the outcome of a Cabinet meeting before it begins. Blair is an example of a Prime Minister who had a lot of power due to a large majority. His Cabinets were reduced in time to 1 hour and he dominated the agenda. He would often make decisions in smaller cabinet committees. This was known as ‘sofa Government.’ He embarked on his own policy agenda with regards to issues such as Iraq and Northern Ireland.
To conclude, the Prime Minister exercises considerable amounts of power over the cabinet. However, the Prime Minister must be careful not exercise too much control in this way as it is important that he retain the loyalty of his Cabinet for the stability of the party.