A Constitution:
(1) regulates the relationship between states and individuals
(2) determines the structure of the state (federel / unitary / regional)
(3) sets up a framework of government (Parliamentary system, bicameral, constitutional monarchy (established in 1688)
Constitutions are primarily about political authority and power (location, conferment, exercise and limitation; among the organs of the state). They are concerned with matters of procedure as well as substance.
Narrow meaning: document having a special legal sanctity and has an overriding legal force.
Wider meaning: assemblage of laws, institutions and customs; the whole system of govenment of a country, the collection of rules which establish and regulate or govern the government. The vaccum caused by the absence of a strong legal foundation is filled by the doctrine of legislative supremacy of parliament.
Legal consequences of an unwritten constitution: doctrine of the supremacy of parliament, no truly federal system, no special procedure prescribed for legislation of constitutional importance, different sources (Acts, Cases, Royal Prerogative, Conventions); constitutional system depends more on political factors and democratic principles.
Aspects of classification: written/unwritten, flexible/inflexible, presidential/parliamentay
Sources - Legislation: Magna Carta 1215 (rights of various classes of the medieval community set out: freedom of the church, of the cities, no unjust taxation of merchants); Bill of Rights 1689 (rights of parliament; removed the King´s right to suspend of dispense with laws, to levy money w/o grant of parliament; to raise and keep an army in times of peace; freedom of speech and of procedings in parliament; rights of subjects to petition the king). Act of Union with Scotland 1707, Parliament Acts 1911 and 1949, Statute of Westminster, Crown Proceedings Act 1947, European Communities Act, Representation of the People Act 1983.
Sources - Case Law: Case of Proclamations (King can no longer themselves create new royal prerogatives); Chandler v. Director of Public Prosecutions (Courts have no power to review the exercis of the Royal Prerogative); BBC v. Johns (Even the courts can no longer create new Royal Prerogatives); GCHQ (Exercise of the Royal Prerogative is subject to judicial review); Writ of Habeas Corpus (right to a fair trial and protection against unlawful invasion of personal liberty); Legislative Supremacy of Parliament.
Sources - Conventions: (= understandings, habits or practices not enforcable by the courts); Queen exercises Royal Prerogative on and in accordance with ministerial advice; Ministerial Responsibility to Parliament; Collective Responsibility; money bills have to be introduced in the Commons first; HoC Speaker shall behave impartially; no Lay Peers exercising judicial tasks of HoL.
Conventions are observed: (1) for the positive reason that they express prevailing constitutional values; (2) for the negative reason of avoiding political (and also legal) difficulties that may follow from "unconstitutional conduct".
Sources - the law and custom of parliament: outside the scope of ordinary law; rules relating to functions, procedures, privileges and immunities; partly statutory and judge-made, but mostly in either resolutions of recordings; no backwoodsmen voting in HoL (standing order)