Labour leadership candidate Lisa Nandy has issued a strong defence of free movement in a key speech at the Royal Society for the Arts, Manufactures and Commerce this afternoon.

Jeremy Corbyn’s party included a commitment to end freedom of movement in its 2017 manifesto, and said it would be “subject to negotiations” post-Brexit in 2019.

The policy to back free movement in a Remain scenario and leave it up to negotiations in a post-Brexit one was adopted despite Labour conference having voted in favour of extending free movement.

“We should have been bold enough to defend free movement, and the opportunities and benefits it brings,” the leadership hopeful told an audience at an event hosted by the RSA.

“But this would have required recognising it has flaws, and not dismissing concerns as simply racist anti-immigrant sentiment. We should acknowledge that over decades governments have used the steady influx of skilled labour to cover up a lack of investment in skills and training in the UK and address this.”

Mounting a full-throated defence of freedom of movement, Nandy added: “I believe in free movement. If it were paired with renewed and radical investment that enabled opportunities for young people, decent jobs, training and skills, then the same concerns would have fallen away.”

“I have fought for the rights of migrant workers in the UK all my life and, unlike Boris Johnson, I know that the so-called Red Wall communities do too.”

Setting out her criticisms of the Brexit debate and the polarisation caused by the EU referendum, Nandy asked why Labour was both “a force for radical change” and “on the back foot defending the status quo”.

The leadership candidate asserted: “Three and a half years later, we’re still on the back foot. We’ve allowed the right to frame the debate into a series of false binaries, and in so doing enabled a fully-fledged culture war to be unleashed.

“The trap was set. You can either be for your country or for the world. And senior Labour politicians rushed headlong into it. It was a serious failure of leadership.

“I know the truth is more complicated than that. My remain voting friends are not liberal elites and my leave voting neighbours are not racist little Englanders. If we fail to recognise that there are valid views on both sides, we let everyone down.

“Winning the argument for a confident, open, internationalist country will take leadership. Thinking big. Not playing it safe. Understanding that the referendum result was a call for more power and control – and that the response should not have been reduced solely to a technocratic debate about single market membership and the rights and wrongs of a customs union.”

With reference to the Salisbury attack in which Sergei and Yulia Skripal were poisoned, Nandy argued that the Labour leadership “failed on Russia” and said: “It was totally wrong that our response to this was to cast doubt on what happened and call only for dialogue.”

She said: “At a crucial moment, we hesitated in condemning an authoritarian regime that supports Trump, invades its neighbours, steals its country’s wealth, interferes in elections in Europe and America, attacks minority communities and then used chemical weapons on the streets of the UK.

“We stood with the Russian government, and not with the people it oppresses, who suffer poverty and discrimination. We failed the test of solidarity. And as a result, we let the Tories get away with their own shocking weakness on Putin’s Russia.”