Plans to reform of the House of Lords have been dropped once again. Here is a timeline explaining the history of Parliament's upper house.
Parliament's origins can be traced to the witans: councils of chief advisers, magnates and religious leaders consulted by Saxon kings.
Two distinct Houses of Parliament emerge - the Commons, composed of shire and borough representatives, and the Upper House of religious leaders (lords spiritual) and magnates (lords temporal).
Abbots and priors sat in the Lords until 1539 but the dissolution of monasteries saw them removed, leaving only the bishops as the spiritual side of the chamber.
The bishops were kept out of the Lords during the Civil War but returned in 1661. The Lords itself ceased to exist from 1649 to 1660. In the 1670s the Commons was officially given the final say on financial matters after attempts by peers to break the convention. And in 1689 the Commons put forward the Bill of Rights, which gave Parliament authority over the king.
Scottish and Irish peers were allowed to elect some of their number to sit in the Lords after the Acts of Union with Scotland (1707) and Ireland (1800).
The number of bishops in the Lords was limited in the late 19th century and most Irish and Welsh bishops in any case stopped sitting in the chamber when their churches broke links with the state. In 1876 the first life peers were effectively created when the sovereign was allowed to appoint law lords.
Crisis over the House of Lords erupted when peers rejected the Liberal government's budget in 1909. The Liberals hit back with laws to strip the Lords of power to reject legislation approved by MPs. The Parliament Act of 1911 said "money" bills became law within a month if peers did not pass them without change. And MPs could force through other bills if the Commons passed them in three successive sessions after a two-year delay.
The Parliament Act of 1949 limited the Lords delaying powers to one year - with MPs only having to pass a bill in two successive sessions.
The Life Peerages Act allowed people of either sex to be made life peers. Allowances for peers' expenses were introduced.
Women inheriting peerages were allowed to sit and vote in the Lords. And people were allowed to renounce their hereditary peerages - a law sparked by calls by Tony Benn, who had become Viscount Stansgate when his father died.
All but 92 hereditary peers are banished from the Lords in what was meant to be the first stage of reform by the Labour government.
Seven options for reform, from a fully elected to a fully appointed second chamber, are put forward but MPs and peers fail to agree on any of them.
Commons leader Jack Straw outlines proposals for a mixture of elected and appointed peers. MPs back two separate plans - one for a fully elected second chamber and another for one which is 80% elected.
The judicial function of the House of Lords is passed to the newly created Supreme Court. The sitting law lords become the first judges in the new court.
27 June 2012
The government publishes a House of Lords Reform Bill, which would make the chamber mostly elected for the first time in its history. The bill will cut the number of members by nearly half and make 80% of peers elected. The remaining 20% will be appointed.
9 July 2012
The second reading of the House of Lords Reform Bill starts. The government faces a possible rebellion of up to 100 Conservative MPs who are unhappy with the bill, which, they say, will result in increased conflict between the changed Lords and the Commons. There is also anger over the government's "programme motion", which would limit the amount of time MPs can spend discussing the issue to 10 days. Labour supports the reforms in the bill but opposes the timetable, arguing the debate needs more time.
10 July 2012
The government drops the programme motion on the bill, amid fears it might lose the vote in the face of Labour and backbench Conservative opposition in the Commons. Ministers insist they will still push for reform, but rebels say they will continue to oppose it. The passage of the bill, if it goes ahead, could be complex and take a long time.
12 July 2012
David Cameron tells backbench Conservative MPs he will have "one more try" on Lords reform but if his party cannot reach a deal he will "draw a line" under the issue.
6 August 2012
Liberal Democrat leader Nick Clegg announces that plans to reform the House of Lords will be abandoned. It follows reports that Mr Cameron's attempts to win round rebels in his own party had failed.