MIGRANT workers help keep down food prices, staff the NHS and contribute billions in taxes, and the LibDems should loudly champion their cause, Willie Rennie will say today.

At his party’s annual conference, the Scottish LibDem leader will tell party activists they must challenge Brexiters head-on by extolling the benefits of inward migration.

It is the political leaders “blindly backing Brexit... we should be sending home,” not people from Poland and Romania, he will tell activists in Dunfermline.

The gathering in is the first for the Scottish party since the general election in June, when it went from one MP to four.

Despite a LibDem failure to achieve a UK-wide breakthrough by campaigning against Brexit and for a second referendum, Mr Rennie will make the issue central to today's event.

He will will call on his party to lead a national debate on the benefits of immigration, and attack the Brexiteers who risk “tanking the economy” by cutting it without a back-up plan.

Mr Rennie will say: “If immigration is not cut with Brexit, then Leavers will feel betrayed because that is what they voted for. If the Conservatives keep that promise, and immigration is cut, it will damage our economy and public services, and even more will feel betrayed because they were not told this would happen.

“Whilst leaders bicker about transition periods and single markets and common external tariffs, the elephant in the room is immigration. In the Brexit vote people were promised fewer foreigners in our country. Yet people were not told the price of that policy. And it is big.

“The price is a shortage of workers to get food from British farm into the shops.

“The price is a shortage of carers, nurses and GPs.

“The price is billions of pounds of lost taxes from these jobs.

“They are already going home and Brexit has not even happened yet.”

A Scottish Government study this week found EU migrants contributed £4.4bn to GDP each year, with each of the 128,000 EU nationals working in Scotland adding £34,400 in GDP.

Issuing a direct challenge to those who would cut immigration regardless of the consequences, Mr Rennie will add: “Some say that too much immigration is a threat to our way of life. But the truth is that not enough immigration is the real threat to our way of life.

“It’s not the workers from Poland, Romania or Bulgaria who we should fear.

“We should fear all those political leaders who are blindly backing Brexit. These are the people we should be sending home.

“The Conservatives do not want a debate over immigration. But we need it and that is what I am calling for today before it’s too late.

“My call today is for people to stand up for immigration. Stand up to save our farms, universities and health service. We shouldn’t be timid. We need this debate now.”

The one-day conference is also due to debate young people in public service, housing, pension inequality, gender neutral school uniforms and health in rural areas.