Tributes are being paid to Tony Benn, one of Britain’s most progressive politicians, who has died at the age of 88.

Benn became an MP in November 1950 and served in the cabinet under Harold Wilson and James Callaghan.

A major figure on the left of the Labour Party, he narrowly missed out on the deputy leadership in 1981 and was a popular public speaker, anti-war campaigner and political diarist.

He retired as an MP at the 2001 general election.

Benn voted strongly in favour of gay rights during his time in Parliament – including the decriminalisation of homosexuality in England and Wales in 1967.

He denounced the Thatcher Government for introducing Section 28 in 1988.

The law stated that a local authority “shall not intentionally promote homosexuality or publish material with the intention of promoting homosexuality” and that schools “could not promote of the acceptability of homosexuality as a pretended family relationship”.

Speaking in the Commons, Benn said: “If the sense of the word ‘promote’ can be read across from ‘describe’, every murder play promotes murder, every war play promotes war, every drama involving the eternal triangle promotes adultery; and Mr Richard Branson’s condom campaign promotes fornication. The House had better be very careful before it gives to judges, who come from a narrow section of society, the power to interpret ‘promote’.

Benn voted for the repeal of Section 28 during the first term of Tony Blair’s Labour Government.

He also voted in favour of equalising the age of consent.

Benn told Socialist Review in 2007: “I’d like to have on my gravestone: ‘He encouraged us.’ I’m proud to have been in the parliament that introduced the health service, the welfare state and voted against means testing. I did my maiden speech on nationalising the steel industry, put down the first motion for the boycott of South African goods, and resigned from the shadow cabinet in 1958 because of their support for nuclear weapons.

“I think you do plant a few acorns, and I have lived to see one or two trees growing: gay rights, freedom of information, CND. I’m not claiming them for myself but you feel you have encouraged other people and see the arguments developing.”

Speaking on equal marriage and the Church of England, Benn said: “When you think of the number of men in the world who hate each other, why, when two men love each other, does the church split?”

Labour leader Ed Miliband led the tributes to an “iconic figure of our age”.

“He will be remembered as a champion of the powerless, a great parliamentarian and a conviction politician,” he said.

“Tony Benn spoke his mind and spoke up for his values. Whether you agreed with him or disagreed with him, everyone knew where he stood and what he stood for.”

Prime Minister David Cameron said: “I am sorry to hear that Tony Benn has died.

“He was a magnificent writer, speaker, diarist and campaigner, with a strong record of public and political service.

“There was never a dull moment listening to him, even when you disagreed with everything he said.”

Deputy Prime Minister Nick Clegg tweeted: “Very sad to hear about the death of Tony Benn. A towering figure in British politics and a fervent defender of what he believed.”