Harriet Harman, feminist and moderniser, declares that Labour is now in safe hands

Records are falling and quizzes are going to have to be rewritten. The Labour Party has asked all its MPs if they intend to stand again at the next election, still probably two and a half years away, so that it can start to choose candidates to replace them.

Hence Harriet Harman’s announcement that she will be standing down whenever Boris Johnson decides to call the election – it will soon be the prime minister’s decision again, once the repeal of the Fixed-term Parliaments Act gains the royal assent.

This is a significant moment in the history of the Labour Party during my lifetime. Harman is the longest continuously serving female MP (although Margaret Beckett has served for longer, she was out of parliament 1979-83); was deputy leader of the party for eight years; and twice acting leader, in 2010 and 2015.

She was first elected in a notable by-election in Peckham in 1982. Michael Foot was the leader of the Labour Party; the SDP had broken away the year before. The Liberal-SDP Alliance, having taken the lead in national opinion polls at the start of the year, was by the time of the by-election in October languishing in third place as Margaret Thatcher rode the post-Falklands wave of economic recovery.

Harman’s opponents in that by-election were Dick Taverne, the former Labour MP, for the SDP, and John Redwood for the Conservatives. She beat them with a large majority, and has represented the constituency ever since.

When she joined the Commons, she was one of 22 female MPs, 12 Labour, 9 Conservative and 1 SDP. As a moderniser, she helped build Labour as an election-winning proposition. As a feminist, she helped raise the proportion of female MPs from 3 per cent to the current 34 per cent. What is more, she will leave a Parliamentary Labour Party that is majority female for the first time in its history.

That is partly the result of her fight for all-women shortlists, which helped achieve the biggest single advance in female representation in the 1997 election. That was also the election that secured a big majority for a New Labour government, which did so much for equalities generally, and in which she was the first ever minister for women.

She was at the heart of New Labour before it was called that. She was shadow chief secretary to the Treasury, deputy to Gordon Brown, the shadow chancellor, between 1992 and 1994, when I remember filming them both for the BBC.

This involved the two of them having a conversation for the cameras about how Labour was going to attack the government. Harman gently teased Brown by asking him which economic league table Britain was bottom of. But when John Smith died, she showed toughness in telling Brown to his face that she would be supporting Tony Blair for the leadership.

It was while she was shadow chief secretary that I first met her research assistant, Ed Miliband, so she was not only at the heart of New Labour, but at the heart of the post-New Labour story as well. The post-post-New Labour period, though, was a different story. Although she presided, as acting leader, over the election of Jeremy Corbyn as leader, it wasn’t the outcome she wanted.

She was blamed after the event for whipping Labour MPs to abstain on the Tories’ welfare bill – a standard tactic of parliamentary procedure that was used by Corbyn, who defied the whip to vote against, to portray himself as a true socialist fighting against the Tory-lite majority of Labour MPs.

In hindsight it was a mistake, but it wasn’t the cause of the election of Corbyn by a large majority in September 2015. If anyone is looking for those who made that possible, it was Miliband, who reduced the role of MPs in leadership elections, and those MPs who nominated Corbyn without intending to vote for him.

Harman survived the Corbyn years, devoting herself to the constructive parliamentary role of chairing the joint committee with the House of Lords on human rights, a return to her founding cause as legal officer for the National Council for Civil Liberties (now Liberty).

Her committee has consistently made life uncomfortable for the government, which is the whole point of human rights law. It is designed to protect the rights of the marginalised and unpopular when governments find it inconvenient. Indeed, her committee will question Dominic Raab, the justice secretary, tomorrow about his plans to “overhaul” the Human Rights Act, one of New Labour’s great reforms.

She was never going to quit while the party was in the hands of the faction against which she had fought her whole career. But now, she said on the radio this morning, “Labour is in good nick and moving forward – I wouldn’t have wanted to leave if Labour was fragile. It’s not. It’s ready to win and ready for government.”

It is typical of her toughness and sense of responsibility that only now does she judge it safe to leave the fight to others.