BORIS Johnson accidentally promised to undo the Tory Government's two-child limit on benefits when he was flummoxed by a question over the rape clause. 

The Prime Minister surprised MPs when he branded the policy an “injustice” that needed rectifying.

The so-called rape clause has been controversial ever since it was first introduced as part of a reform to benfits by George Osborne back in 2015.

It means that any child born as a result of rape is exempt from the two-child limit to tax credits or universal credit.

In response to a question from Jeremy Corbyn, the Prime Minister seemed unaware of the existence of the two-child limit.

READ MORE: 'Rape clause' has affected 50 Scottish women, figures reveal

The Labour leader said he hoped the Tory chief's reply meant he was going to end the two-child policy.

But SNP MP Alison Thewliss, a long-term campaigner to end the clause, assumed Johnson had misspoken.

She tweeted: “My guess is he doesn’t know what he’s talking about. The two-child limit and the rape clause stigmatise, impoverish and must be scrapped,” she had said.

A No 10 source later ruled scrapping the clause.

Having seemingly been proved correct, Thewliss said: “This is a Prime Minister woefully ignorant of the devastating policies that he voted for.

“The pernicious two-child limit forces families into a poverty trap and it must be scrapped along with the rape clause.

“It seems impossible that the Prime Minister can be unaware of the damaging impacts of such a policy given the number of charities, groups, cross-party members and others who have continually raised it over the past months and years.”

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The Glasgow Central MP added: “The continued damage that this policy will inflict on families and communities across the UK is frightening, with CPAG estimating that ending the two-child limit would mean 300,000 fewer children in poverty by 2023/24 and would prevent one million children being pushed even deeper into poverty.

“The Prime Minister should keep his promise and ditch this wicked policy now.”