Peers' battle to stay in the Commons
Fifty years ago this summer - 31 July 1963 to be precise - Labour politician Tony Benn won the right to renounce his hereditary peerage, following a lengthy campaign.
The son of a hereditary peer, Mr Benn was the Labour MP for Bristol South East when he inherited the title of Viscount Stansgate in 1960 - and with it, a seat in the House of Lords.
He was not obliged to take up the place - many hereditary peers did not - but the law did require him to quit the House of Commons, where he'd sat as an MP for 10 years. But he did not want to leave.
Mr Benn had been trying to get the law changed since first being elected an MP in 1950, but it took years - and much debate - to get the measure through Parliament.
He says: "The real issue was not about me at all; it was about whether Bristol South East was entitled to elect who they liked as a member of Parliament... And I used that constitutional argument as strongly as I could."
A by-election was held in Bristol South East in April 1961. Mr Benn fought and won, with an increased majority - but he was still barred from the Commons.
An election court awarded his place to the Conservative candidate he had defeated in the poll.
A few years earlier, in 1958, the first life peers were created in the House of Lords.
But the Conservative government left out the matter of renouncing hereditary peerages because it did not want to burden the bill with too many things and not get it through.
Constitutional expert and Conservative peer Lord Norton of Louth believes there was not much appetite for further change.
"There wasn't any great enthusiasm for it. It was simply the agitation of Benn and potentially the embarrassment caused by the fact that here was someone who'd been elected to represent the constituents of Bristol South East who'd been disbarred from fulfilling that role."
The mood in Parliament changed by 1963, and the Peerage Act, allowing renunciation of peerages, became law on 31 July that year.
Mr Benn disclaimed his peerage the very same day, and went on to win another by-election - returning to the Commons and serving as Bristol South East's MP until 1983, when the seat was abolished.
He then went on to become the MP for Chesterfield.
The 1963 Peerage Act also had a significant impact on the Conservative Party.
In October 1963, Conservative Prime Minister Harold Macmillan announced he was stepping down due to ill-health - prompting a leadership campaign.
Back then Tory leaders were chosen through a policy of "emergence".
One leading contender, Viscount Hailsham, disclaimed his peerage in a speech at Tory conference.
But it was another peer, the Earl of Home, who emerged as leader.
Shortly after becoming prime minister he renounced his peerage then won a by-election in Perth, enabling him to sit in the Commons as Alec Douglas-Home.
Dr Meg Russell, author of The Contemporary House of Lords, says: "It cemented finally the convention that prime ministers can only be drawn from the Commons.
"The fact that he felt the need to renounce and move to the Commons was a clear indication that it was no longer considered possible or acceptable to be a prime minister in the Lords."
But although the 1963 Act permitted hereditary peers to renounce their titles, no such measure has ever been introduced for life peers. Most of the more than 800 Lords are now life members, but only the Bishops are permitted to retire.
Dr Meg Russell thinks that enabling life peers to retire is the "necessary next step".
She says: "Today one of the most obvious problems is the fact that life peers cannot permanently retire and the chamber is getting bigger and bigger.
"They would quite like the ability to retire when they feel they've reached an age when they have nothing further to contribute and that would help to bring the size of the chamber down."