11TH CENTURY: Origins of Parliament in the Witans; councils consulted by Saxon Kings and attended by religious leaders, magnates and the King's own ministers.

13TH CENTURY: Attendance began to include representatives of counties, cities and boroughs.

14TH CENTURY: Two distinct houses emerged. One composed of shire and borough representatives became known as the Commons; the other of religious leaders (Lords Spiritual) and magnates (Lords Temporal) became known as the Upper House.

15TH CENTURY: Membership of Lords Temporal had by now become almost entirely hereditary and male, members being summoned by writ rather than chosen by the monarch. The Lords Temporal became known as 'peers' i.e. equal among themselves but with five ranks - Duke, Marquess, Earl, Viscount and Baron.

16TH CENTURY: Until the suppression of the monasteries in 1539 the Lords Spiritual consisted of bishops, abbots and priors. After 1539, only bishops attended and the Lords Temporal formed the majority for the first time.

17TH CENTURY: In 1642 during the Civil War bishops were excluded from the House of Lords but returned by the Clergy Act 1661. In 1649 the House itself ceased to exist but resumed separate sittings in 1660. The Commons pre-eminence in financial matters was given an official basis in the passing of resolutions in 1671 and 1678 after attempts by the Lords to breach the convention. The 1689 Bill of Rights, initiated by the Commons, established the authority of Parliament over the King.

18TH CENTURY: The Acts of Union (1707 with Scotland and 1800 with Ireland) entitled Scottish and Irish peers to elect representatives from among their number to sit in the Lords.

19TH CENTURY: The Bishopric of Manchester Act 1847 (and later Acts), limited the number of bishops entitled to sit. Most of the Irish and all the Welsh bishops ceased to sit when their respective churches were disestablished in 1869 and 1920. Retired bishops cannot sit or vote in the House. The Appellate Jurisdiction Act 1876 enabled the sovereign to create Lords of Appeal in Ordinary (Law Lords) to fulfill the judicial function of the House of Lords. Unlike bishops, retired Law Lords can continue to sit and vote. They were, in effect, the first Life Peerages.

20TH CENTURY: In 1909 the Lords rejected the Liberal Government's budget. The Liberals then introduced a bill to end the Lords' power to reject legislation approved by the Commons, which was passed under the threat of a large creation of Liberal peers. The Parliament Act 1911 provided that:

• Money bills approved by the Commons became law if not passed without amendment by the Lords within one month.

• Other Public Bills, except one to extend the life of a Parliament, became law without the consent of the Lords, if passed by the Commons in three successive sessions, providing two years elapsed between Second Reading and final passing in the Commons.