"For a Prime Minister to dominate the whole business of governing, he or she needs a formidable equipment and some good fortune"
PJ Madgwick

The Prime Minister of the UK is the leader of the executive in the House of Commons. He/she is invited to become the Prime Minister by the Monarch who appoints him/her to be his/her presense in the Cabinet. The Prime Minister is supposed to be 'Primus inter pares', first amoung equals, but whether this still exists is an often disputed point.

Origins

The role of the Prime Minister came about in the early days of the British Government in the reign of George I when the he stopped attending the meetings of his appointed cabinet. After the Glorious Revolution of 1688 Parliament passed a Bill of Rights which cut the Monarch's power. The Monarch was allowed to appoint a cabinet to take on the powers that he wasn't allowed to use (but this cabinet had to come from the party in the Commons that had a majority of seats). The monarch created a leader of the cabinet to represent his interests in the cabinet meetings when he wasn't there. This leader was, by convention, the First Lord of the Treasury since he had the most power (people who control the money tend to have power). This is still the term for the Prime Minister today since no one actually got round to changing it, people just call him/her the Prime Minister by convention. The term Prime Minister was originaly used as a sarcastic, almost derogatory, term to describe the appointee as the "Monarch's pet" or the favourite. Though it is true that the First Lord was called the Prime Minister they didn't have the same sort of power as the modern Prime Minister.

Prime Ministerial Style

Professor Philip Worton in 1987 described four different styles of Prime Minister.

Innovator
Innovators use their position to attain a set of objectives. These can be party objectives but are more often than not personal ones. For example, Heath and Thatcher.
Reformer
Reformers want to gain power so that they can reform things. This is shared by their party who want these reforms. For example, Clement Attlee.
Egoist
Egoists want power because of the adrenaline rush they get from the popularity and the power. They rarely have any goals excpet for those that will guarentee their continuation in office. For example, Harold Wilson (according to The Crossman Diaries).
Balancer
Balancers are those Prime Ministers who are trying to stop the boat from rocking. They are not aiming at anything but keeping the country/government/party from splitting at the seams. They just want stability. For example, Major and James Callaghan.
Some of these styles are thrust upon the Prime Minister (such as John Major being a balancer) by their circumstances. They have to adopt that style due to issues that are present at the time. It is possible for the Prime Minister to be in several of these catergories at once.

Roles

The PM has numerous roles which are often derived from the Royal Prerogative which are powers that have been handed down from the Monarch.

As you can see, the Prime Minister has a good deal of power in the UK political system. He has a number of others apart from those above that are called Prerogative powers and all in all he is the most powerful (wo)man in Britain. One potentially dangerous thing is the fact that (s)he can do almost whatever he/she wants. There is no check on the Prime Minister and he has almost total control over his backbenchers. The opposition in the UK is abismal at the best of times and lacks any substantial power. The second chamber, the House of Lords, has been reformed to the point that it can no longer stop the House of Commons which the Prime Minister controls. This control of the Commons occurs because the electoral system leads to the winning party often having a majority in the Commons meaning that the Prime Minister can force through almost any thing he/she wants; they become an elected dictator. The only things that can really stop the Prime Minister are:
  1. Not enough time
  2. backbench revolt
  3. huge dissent in the general populace leading to mass riots
  4. a coup by the military
  5. a Minister revolt (very unlikely)
  6. sudden death/assasination
As you can see by the list, there are not really any real checks on the Prime Minister's power. Though public opinion is a very powerful force in the UK it doesn't stop the PM on a lot of issues.

It is impotant to note that there is no written (codified), entreched constitution in the UK (Dayv's write up is mostly accurate) and as such there are no statutes that are above other laws (unlike in the US where the Constitution is codified and entrenched making it above other laws and difficult to change). This means that Parliament is sovereign meaning that Parliament has the power to do anything. This includes changing previous laws so Parliament (under the control of the Prime Minister) can change Britain drastically in a totally legal way. So, for example, Tony Blair could wake up one day and decide that he wanted to get rid of the Houses of Parliament and make himself the Head of State (abolishing the Queen in the process). This would be perfectly OK by the laws of the land since Parliament can make any law it wants including those that repeal old laws. This would never happen though because the British people would never allow it and it is unlikely that the military (or the people) would let the politicians do anything like that.


If i find any more random notes on the Prime Minister then I shall add them later.