A convention is an accepted way in which things are done
A convention is an accepted way in which things are done. They are not written down in law but tend to be old, established practices – the way they have always been done. Though these conventions are not set in legal stone, their very existence over the years has invariably lead to the smooth operation of government.
Conventions are defined by AV Dicey as "...understandings, habits or practices which, though they may regulate the... conduct of the several members of the sovereign power... are not in reality laws at all since they are not enforced by the courts."
An explanation as to the function of these conventions is offered by Sir Ivor Jennings when he notes that "they provide the flesh which clothes the dry bones of the law; they make the legal constitution work; they keep it in touch with the growth of ideas."
Conventions are a prominent characteristic of the British constitution. These rules are sometimes referred to as "rules of constitutional morality". Conventions represent the important rules of political behaviour which are necessary for the smooth running of the constitution.it is not only in the constitutional arrangements of the united kingdom that conventions are important ;K.C Whearne in ‘Modern Constitution ‘  states that ‘in all countries usage and conventions are important and .....in many countries which have constitutions usage and convention play as important a part as they do in England’.
For dicey, conventions regulate the residual discreationary powers of the Crown .conventions also regulate the previliges of Parliament.Constitutional developments has moved power from the soverighn to the ministers ,not as servants of the Crown, but ato Parliments representative of the people.the Bills of Rights 1688 and the Revolution Settlement shifted the balance of power from the sovereign to Parliament.
There is a convention to the effect that that the royal assent should be given to the Bills which have been approved by the Houses of Parliment.an alternative formulation of the convention stipulates that the sovereighn should exercise his prerogative powers following the advice of ministers.
Jenings take account of changes which had become more apparent int he 20th century . for jeninings it is not so much pereogative which requires regulations, as cabinet government. The cabinet and the primeminister are conventional institutiuons.indeed it is convention which recognises the role of the opposition. A reflection of thei s is that in Parlimentary debates the Speakers asks contributions alternately from those on the government benches , and those on the opposition benches.
Jenings had a gift for the use of metaphor. He wrote that conventions ‘provide the flesh which clothes the dry bones of the law’ 
He also identified two basic functions of constitutional conventions. They ‘enable a rigid legal framework-and all laws tend to be rigid- to be kept up with changing social needs and changing political ideas ’.  Secondly, conventions enable those who govern to ‘work the machines’.  the practice of ‘pairing’ involves an MP from the government party and an MP from an opposition party agreeing not to vote in divisions in th e Commons.
CONVENTIONS AND THE COURTS:
Dicey maintained that conventions could be distinguished from law because the courts would not enforce conventions. The case law indicates that, while the courts do not enforce conventions ,they do recognise them and, indeed, on occasion, use them as an aid to the construction of statutes.
The case of Madzimbamuto v Lardner-Burke  1 AC 645 a court has refused to enforce a convention. The judicial Committee of the Privy Council was asked to take account of the convention Which stipulates that the Westminster Parliament only legislate for a Commonwealth country at the request, and with the consent of that country’s government. The government of Southern Rhodesia(now Zimbabwe)had made an unlawful unilateral declaration of independence. In reaction to this Southern Rhodesia act 1965 was enacted at Westminster. This statute, which reasserted the right of the Westminster parliament to legislate for Sothern Rhodesia, had not been requested by the Southern Rhodesian government. The case raised the legality of regulations made by the government of Southern Rhodesia .The Privy Council was faced with a conflict between the legislative supremacy of Westminster Parliament and the convention. Unsurprisingly, the Privy Council held that the 1965 statute, although passed in breach of the convention, was valid.
Statutes are part of the British Constitution which means conventiona are recognised source of the britis constitution.. further more ,conventions are flexible as occasionally they are set aside. For example the convention of “collective cabinet responsibility was temporaraliy set aside in relation to the 1975 EEC national referendum"  . The referendum concerned “wheather the United Kingdom should remain in the EEC".  At the time the “Labour Cabinet"  was divided over this issue which is why thw Prime Minister set the convention aside.
It can be argued that even though courts do not “enforce constitutional conventions  ";they have at some point recognised and establisghed them. An example of a case wherby the courts have used conventions is in “Attorney- General V Jonathan Cape Ltd[ 1976]1 QB 752.  "in this particular case the Attorney-General stoopped the publication of abook which happened to be the diary of Richard Grossman who died in “1960s". The diary consisted of discussion in cabinet and this was a breach of confidence. The government related its case upon"the convention of collective responsibility, arguing that this necessarily required that cabinet business remain confidential to cabinet ministers."the jugje gave his permission for the publication of diary as it “dealt with matters of historical interest"  .therefore the convention was “a crucial strand of the argument, but not the law itself".
Another case which proves the fact that conventions are a recognised source of not just the British Constitution but any constitution is “Reference Re Amendment of
Conventions are really important part as they display how the UK constitution must be “pieced together." They are something that must be obeyed whilst in power. They deal with relationship between the" different branches of the Central government, the crown, the Executive , Parliament, the Civil Service, the Prime Minister and the Cabinet"  . The prime minister especially is part of conventions as is The Cabinet which suggests that our parliament is made of conventions. Our Legislative System is heavily relied upon conventions. For example it’s a convention that the “Queen must assent to a bill passed by both Houses of Parliament"  . However, The Crown can refuse to give her Royal Assent. Furthermore, it’s convention that the Queen must appoint a Prime Minister.furthermore, it’s convention that Queen must appoint the prime minister. It can therefore be suggested that Conventions play a huge part in Parliment whis is some times compared to a constitution and theat the conventions are a recognised sourse of the British Constitution.
Constitutional conventions have gained the ground of constitutional law for a long time now. It is already stated in the Dicey's work that rules which make up constitutional law include two sets of principles: the law of the constitution and convention of the constitution  . Britain is particularly known for its constitutional constitution due to their central place in the workings of the government. However, the "unwritten" nature of the British constitution should not mislead us to assume that conventional rules are originality of countries without formal constitution.
Conventions constitute a major element of the British Constitution .these are the unwritten principles of political practices and customary principles of constitutional behaviour which have developed in the course of time. J.S Mill described them as the “Unwritten maxims of the Constitution." However, unlike the laws, they are not recognised and enforced by judicial courts. But they play a very signinificant role in the actual working of the British political institutions. They are generally observed as they are backed by traditions and public opinion. The well known conventions in Britain are:
The king or Queen should exercise his/her legal powers on the advice of the Cabinet headed by the Prime Minister.
The King should appoint the leader of the majority party in the House of Commons as the Prime Minister.
The king should dissolve the lower house of the Parliament on the advise of the Prime Minister.
The king should give his assent to all the bills passed by the parliament.
The cabinet is collectively and individually responsible to the house of commons.
Key elements of the British constitution are based on non-justifiable conventions_ that are not enforceable by the judges. Such conventions govern the basic matters that are fundamental to a British parliamentary democracy. Unwritten conventions underpin the transfer of power from individual monarchs-who are still recognised by British courts a s the ultimate legal source of all executive authority –to government and ministers democratically responsible to an elected parliament. In the British system of government other conventions, equally fundamental, play an important role in preserving the independence of the judiciary.
Yet in spite of the importance of these conventions in the British system, no judge will, and no police can, enforce them. The survival of an unwritten constitution thus depends, not on the exsistance of enforceable rules, but on ‘form of self and mutual regulation’.7
British Politics and the British Constitution have many political conventions attached to it which have developed and been accepted over the years.
There have been times when conventions have been given legal status. From the time of the English Civil War when Parliament clashed with king over finance, it was accepted that money bills/acts came from the House of Commons. This was given legal status in 1911 with the Parliament Act that stated that parliamentary finance bills/acts must originate from the House of Commons.
Some interesting conventions:
It is accepted that a departmental minister will resign if he/she loses the confidence of the House of Commons (i.e. within their own party). Usually, pressure is put on the person concerned to resign, as a sacking looks bad. In recent weeks, pressure from non-governmental sources (though primarily the media) has tried to tarnish the name of Stephen Byers, the Transport Minister, claiming that he has lost the confidence of the House. However, the simple fact is that Byers has kept his place simply because there has been no public party revolt against him – hence, why he has not resigned.
It is a convention that the queen will accept the legislation passed by the government. In the past, the fear of what happened to Charles I has usually ensured a harmonious relationship between monarch and Parliament! When Charles II became king in 1660, the rule of thumb was for Parliament to give the king enough money per year to maintain a royal lifestyle but for him not to get involved in politics. This worked tolerably well and monarchs and Parliament had usually worked well since then especially as Parliament held the monarch’s purse. Now in the C21st, it is just accepted that the queen will give parliamentary legislation the Royal Assent. It is almost beyond belief that she would not do so – the constitutional crisis this would create would be huge. The public backlash against an unelected person rejecting what a democratically elected government has pushed through would almost certainly be massive.
It is a convention that if something in government goes wrong, the cabinet will all sing the same song and support the minister who may be receiving all manner of criticism from the media. This has been very apparent with the recent history of Stephen Byers – all his cabinet colleagues have leapt to his defence over the problems he has recently faced.
Conventions can be changed, as they have no legal status. But they tend to be tolerated as they allow the system to work
http://www.historylearningsite.co.uk/clear. gifConventions that do not have the force of law
There is a strong element in British constitutional affairs of things happening just because this is the way they have always been done, or at least have been for a very long time. Tradition dictates that the State Opening of Parliament must begin with Black Rod, the monarch’s messenger, having the door to the Commons chamber slammed in his face when he comes to summon members to the House of Lords. This symbolises the constitutional supremacy of the elected house, which is able to defy the wishes of peers.
The conventions also cover the code of conduct for ministers of the Crown, who are expected to conform to certain standards of behaviour. A secretary of state who has lost the confidence of the House, particularly of those on his or her own side, is expected to do the decent thing and resign. Similarly, a minister who is found to have told a deliberate untruth has to go. The conventions are not legally enforceable, but have been almost invariably observed throughout history. 
An example of convention that has been given a legal status states that “parliamentary finance bills/Acts must originate from the House of Commons"  . The fact that this convention has a legal status suggests that it’s a recognised source of the British Constitution.