Prime Ministers do not have a free hand in choosing the members of their Cabinet as a variety of considerations need to be taken into account in appointing Ministers. Choosing those who will make up the cabinet is considered to be one of the most important powers of the Prime Minister. However, the PM does not have a totally free hand in this matter. Labour PMs face formal limitations but all PMs must be careful to include all ideological wings of the party in making up their cabinet. It is also expedient to include the party’s “big beasts” as leaving a major figure on the backbenches could lead to a leadership challenge. Major found when he was forced to include those who disagreed with his policies, such as Portillo and Lilley. Even Blair’s Cabinet has included ministers whose “old” Labour views are well attested, such as Prescott, and Beckett. PMs also have to consider the demographics of the cabinet in terms of gender, ethnicity and regionality. The limitations on a PM in choosing a coalition cabinet are obviously of a much higher order. All these considerations will limit the PM’s power over the Cabinet.
The Prime Minister also faces limitations to his power of patronage when he decides to reshuffle the cabinet. They have to be careful not to appear to completely change the whole Government. Harold Macmillan in the 1960s changed the majority of his Cabinet in what jokingly became known as the night of the long knives! This is very risky because it could appear dangerously de-stabilising and cause a great deal of resentment in the backbenches. If they are reshuffling in order to bring in rivals to silence them it may not work. Gordon Brown brought in rival Blairites with the hopes of winning them over and uniting the party behind him. It didn't work. There were rumours of plots and resignations began. Rebalancing the Cabinet can worry rival wings of the party is not handled well. Demoting Ministers is also very risky. Big beasts especially can be potentially dangerous rivals on the backbenches. Major got rid of his Chancellor Norman Lamont for example, who became an opponent. Blair had Robin Cook and Clare Short resign and become thorns in his side.
The volume of business involved in government makes it impossible for even the most control freak of Prime Ministers to disregard his or her colleagues. PMs who do ignore their cabinets can be removed by them. This was the case with Thatcher. On 1 November 1990, Sir Geoffrey Howe, one of Thatcher's oldest and staunchest supporters, resigned from his position as Deputy Prime Minister in protest at Thatcher's European policy. Her former cabinet colleague Michael Heseltine subsequently challenged her for the leadership of the party, and attracted sufficient support in the first round of voting to prolong the contest to a second ballot. Though she initially stated that she intended to contest the second ballot, Thatcher decided, after consulting with her Cabinet colleagues, to withdraw from the contest. She resigned shortly after.
The final point to consider when explaining the limitations to the Prime Minister’s power over the Cabinet is that the Prime Minister will want to minimise the risk of an embarrassing defeat. If his cabinet rallies against him it is likely the information would be leaked and the press would find out. Members of the Cabinet often aspire to replace the PM at some time in the future and are therefore eager to avoid being seen as a PM “puppet”. Therefore it is in the Prime Minister’s best interest to make sure their ministers will genuinely support their policies. He will have assessed likely opposition and modified any aspects of the policy that are easily criticised. The cabinet prevents the Prime Minister from passing policies without considering the opinions of his colleagues.
Overall, it is in the Prime Minister’s best interests to not exercise too much power over the cabinet because this could lead to his downfall. It is certainly true that the role of the executive as a whole has increased a great deal since the end of World War II, but the apparent dangers of a more personal power attached to the Prime Minister should not be overestimated.