Remain campaigners made a ‘terrible mistake’ by refusing to engage with the debate on immigration during the EU referendum, a former minister has said.

Anna Soubry, a passionate member of the In team, said her side was guilty of sweeping aside concerns about migration while playing up fears about the economy.

The former business minister said: ‘Remain refused to engage on immigration; that was a terrible, terrible mistake.’

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Anna Soubry (left) told the documentary: 'Remain refused to engage on immigration; that was a terrible, terrible mistake.' She was sacked by Theresa May (right) when she became prime minister

Miss Soubry, who was sacked in Theresa May’s reshuffle, said it was a serious error to ‘keep on about the economy’ because it made people ‘bored and tired’.

She added: ‘It was like we kind of made and won that argument, so then the vacuum appeared and then bang, in they came with their killer card, which was immigration and we refused to engage in it.’

A MINISTRY FOR IMMIGRATION? An Immigration Ministry should be created, a report suggests. A ‘Department for Immigration and Integration’ would cut numbers coming in and make sure new arrivals do not overwhelm certain areas. The Policy Exchange think-tank said it would manage the effects of Brexit, which some fear will lead to a surge in immigration before the UK finally leaves. It also suggested allocating a ‘unique person number’ to every citizen to improve the knowledge of who is entering and leaving. David Goodhart, author of the report, said: ‘We have to urgently address the resentment that people feel about the fact that some migrants use Britain as a sort of economic transit camp.’ Advertisement

Miss Soubry said she suspected by the end of May, just under a month before the June 23 poll, that her side might not win. ‘I’d be saying [to people] EU referendum, in or out? And they’d go, “I’m out, I’m out” ... and people were shouting, get these immigrants out,’ she said.

‘And that’s when I thought, oh my goodness me, this is really seriously dangerously bad.’

She made the comments in BBC documentary Brexit: The Battle For Britain, which screens at 9pm tonight on BBC2.

In the programme, former Cabinet minister and Remainer Ken Clarke attacked David Cameron for being ‘reckless’ by pledging to hold a referendum.

The former justice secretary said: ‘I was not consulted, I was only a member of the Cabinet. I read about it in the newspaper [and] we had a row about it, but it was a done deal.

‘I think it was the most reckless and irresponsible decision to announce that he was going to hold a referendum in a few years’ time.’

Jeremy Corbyn was also accused of sabotaging the Remain side, despite claiming to be committed to supporting staying in the EU.

Will Straw, who headed the Britain Stronger In Europe campaign, said it had taken six months to get a meeting with one of the Labour leader’s advisers.

Asked what he thought Mr Corbyn’s attitude to the UK’s EU membership was, Mr Straw said: ‘He was lukewarm about it.’

Labour grandee Lord Mandelson savaged Mr Corbyn and his team in the documentary.

Jeremy Corbyn (left) was savaged by Lord Mandelson over the strength of his support for the Remain campaign. Will Straw (right) said Corbyn had been 'lukewarm'

The peer said: ‘We were greatly damaged by Jeremy Corbyn’s stance, no doubt at all about that. I mean not only was he most of the time absent from the battle, but he was holding back the efforts of Alan Johnson and Labour in the campaign.

‘I mean they felt undermined, at all times. They felt actually their efforts were being sabotaged by Jeremy Corbyn and the people around him.’

Gisela Stuart, the Labour MP who co-chaired the Vote Leave campaign, said there had been an ‘unravelling of the Labour heartlands not feeling that the Labour Party was representing them’ and this had been a ‘real problem’ for the Remain side.

Meanwhile Craig Oliver, former director of communications at Downing Street, revealed Mr Cameron discovered Boris Johnson was going to campaign for Leave only 15 minutes before he announced it publicly.