THERESA May’s departure from Downing St should lead to radical immigration reform following a “dismal decade of dreadful” policies, the SNP has insisted.

Stuart McDonald, the party’s immigration spokesman, claimed the Prime Minister’s policies created “burning injustices” rather than tackling them during her time as Home Secretary and in No 10.

He criticised the “numbers-obsessed” Home Office for pursuing “restrictive” policies regardless of the consequences on families, the education system or the economy.

His comments came as the SNP tabled a motion which claimed Mrs May’s legacy would be her “hostile environment policy and her unrealistic and damaging net migration target”.

Speaking in the Commons, Mr McDonald said Parliamentmust “draw a line under a dismal decade of dreadful and sometimes disgraceful migration and asylum policies”.

He told MPs: “The plain truth is the Prime Minister takes a massive share of responsibility for those policies which were driven by her awful net migration target and her ramping up of the horrendous hostile environment policies, the twin pillars of her drastic reign at the Home Office.

“Rather than tackling the burning injustices, right across the field of immigration and asylum policy, her policies created them.”

Parliament, the MP for Cumbernauld, Kilsyth and Kirkintilloch East argued, also needed to “take its share of the blame”, adding MPs “not only failed to oppose but they actively cheered her on”.

He branded the Government‘s target to reduce net migration to tens of thousands as “a load of utter baloney”, adding: “It was a number plucked from thin air that was utterly unachievable and undesirable from the outset.

“It created a numbers-obsessed Home Office pursuing ever more restrictive policies regardless of the damage to families, to our higher education system, to our economy.”

Mr McDonald cited the Windrush scandal, before turning to the EU settled status scheme, adding: “If we don’t learn the lessons from these disastrous mistakes, we are bound to repeat them and there is a serious risk that the Government is going to do just that with the three million.”

But Caroline Nokes, the Immigration Minister, defended the Government’s record and said workers’ skills rather than where they came from would matter in the future post-Brexitsystem.

“The future system will focus on high skills, welcoming talented and hard-working individuals, who will support the UK’s dynamic economy, enabling employers to compete on the world stage.”

Ms Nokes reiterated that the Migration Advisory Committee had been asked to advise on salary thresholds, including whether there was a case for regional ones.

On the EU Settlement Scheme, Ms Nokes said the message had been that the Government wanted EU citizens to stay, describing the system as “simple and straightforward”.

Afzal Khan, her Labour Shadow, said: “As we look back on the Prime Minister’s tenure as Home Secretary and then as Prime Minister, we reflect on the fact that she was architect of a cruel and ineffective immigration system, which will reverberate through the lives of our constituents for generations.”

He said a Labour government would also “consider whether we need to close Dungavel detention centre” in Scotland.

Conservative backbencher Douglas Ross said a scheme easing visa restrictions on agricultural workers from outside the European Economic Area should be extended to the fishing industry too.

The Moray MP raised the case of a constituent who was “unable to run his business”.

Joanna Cherry, the SNP’s justice and home affairs spokeswoman, warned of a “demographic timebomb” for Scotland as she argued it was “time for immigration policy to be made in Scotland”.

She added: “We know that Scotland’s future lies as part of a Europe of free trade and free movement of people. All the evidence shows that the Scottish economy benefits from immigration.”