The Labour leader was addressing his party’s MPs for the first time since the bruising loss and a subsequent botched reshuffle left his authority diminished.
Speaking to a meeting of the Parliamentary Labour Party, Sir Keir praised the electoral successes Labour did have on ‘super Thursday’, including in Wales.
But he said the party couldn’t shirk away from where it had gone backwards among voters, and described the Hartlepool result in particular as a bitter disappointment. He said the party needed to modernise and speak to the Britain of the 2020s and 2030s.
But to change the country Labour had to change itself, he added, to face outwards to the voters not inwards.
He told MPs: “I didn’t come into politics to tinker around edges. I came into it, as all of you did, to change lives and change Britain. This is a once in a generation moment. We need to build a post-austerity, post-brexit post-pandemic Britain."
He is understood to have pointed to former Labour prime ministers including Clement Attlee and Tony Blair as leaders who had the ability to look to the future and set out a vision of a transformed society.
He also talked about creating good, skilled jobs across the UK, tackling the climate crisis, ensuring that every child has access to a first class education, as well as pushing power and opportunity out of Westminster.
Last week his deputy Angela Rayner warned that voters had told her that they did not know what Sir Keir stood for during the election campaign.
During his lengthy reshuffle, Sir Keir sacked his shadow chancellor and chief whip. But he was forced to give Mr Rayner so many new roles, after word leaked she had been demoted, that she now has a 24-word-long job title.
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