The power of the British Prime Minister can vary according to both circumstances and how effective the holder of the post is. There are a number of aspects to this:-
A Prime Minister who has just won a general election will have prestige with their Party and Cabinet colleagues.
This is especially so for Prime Ministers, such as Margaret Thatcher and Tony Blair, who won more than one election.
It is always expected that the Government will have some unpopularity mid-term between elections. However, if they receive poor opinion poll ratings, by-election defeats and poor local election results they will affect the Prime Minister’s authority.
The disastrous local election results in 1990, after the implementation of the poll tax, undermined Thatcher and continued by-election defeats affected Major.
The stresses of the job may now lead Prime Ministers to decide to retire after about 10 years and not just after a general election defeat.
The announcements by Tony Blair, David Cameron and Theresa May that they would not be leader going into their next election weakened their power. Debate shifted to who would take over? when would they go? as the anticipated date got closer.
The Prime Minister’s resources and staff in No 10 have gradually increased. So, the PM’s ability to exert control over the Government is easier. However, the extent to which Prime Ministers want to do this has varied.
For example, Tony Blair created strong control, even extending to having No 10 vet the speeches that Ministers were about to make. David Cameron, partly in reaction against this, reduced No 10’s interventions, but soon found that he had lost control over the Health Secretary’s controversial plans to reorganise the NHS and so reinstated some of these.
Margaret Thatcher kept strong control, keeping up with everything that was being decided in each Cabinet Committee, whereas John Major wanted a more cooperative style and more discussion in Cabinet.
Even with more resources, the Prime Minister cannot intervene in every issue and has to be selective. Also, his or her ability to get involved varies according to what they are interested in and how much experience and understanding they have of topics.
Events can either enhance or destabilise a Premiership.
Thatcher had problems with public support and her Party until her success with the Falklands War in 1982. But her successor, John Major, never really recovered from being the first Conservative Prime Minister to devalue the £ in 1992. Tony Blair was the only Labour Prime Minister who did not have to deal with an economic crisis.
Relationships with other Cabinet Ministers have an impact on the power of the British Prime Minister.
Keeping Cabinet unity is important but tough. Some Ministers may have been rivals for the leadership in the past or may have important disagreements with the Prime Minister over policy.
For example, Gordon Brown was given an enhanced role as Chancellor of the Exchequer under Blair. Brown was able to control considerable areas of public policy, but the relationship between them became difficult and Blair never felt strong enough to resolve this by sacking him.
In contrast, the relationship between Cameron and his Chancellor of the Exchequer, George Osborne was very close. Some would say too close, in that David Cameron would never sack his friend.
The Cabinet collectively can bring down the Prime Minister.
When Margaret Thatcher was challenged for the Conservative Party leadership she failed to win on the first ballot. After that, it was Cabinet Ministers who told her that she had to go. But, the Cabinet never combined to remove Brown despite problems within the Government and in the opinion polls.
Divisions within the party nationally or within the Parliamentary Party can undermine the Prime Minister.
Harold Wilson was careful to manage the Labour Party from the centre and made party unity a priority.
Tony Blair was able to ignore the left of the party because of his large Parliamentary majority and electoral success but he never really recovered his prestige after the decision to go to war with Iraq split the party.
John Major was damaged by the split in his party and Cabinet .over Europe and even lost his Parliamentary majority for a period when a small of group of Conservative MPs lost the whip.
David Cameron was able to ignore the right wing of his party under the Coalition, as the Liberal Democrat provided a secure Parliamentary majority.
Theresa May lost the Conservative party’s majority in the 2017 General Election and had to work with her own party, deeply divided over Brexit, and the Democratic Unionist Party (DUP) who agreed to prop up her government.
The 2010-2015 Coalition weakened David Cameron’s power to appoint ministers and to get some policies through, as these needed the approval of the Liberal Democrats. But, on the other hand, his natural inclination to get a consensus worked well within a Coalition Government.
Prime Ministers without a majority, as Harold Wilson experienced after February 1974, have limited power to get policies through.
When James Callaghan lost his Parliamentary majority as a result of by-election defeats he had to make compromises with the Liberals to stay as Prime Minister.
