Theresa May has been warned the Conservative Party would “not be forgiven for a generation” if it experiments with its post-Brexit trade policy.
Nicky Morgan and Ken Clarke were among the senior pro-EU Tories who urged the Prime Minister to retain the option of a customs union between the UK and EU, amid concerns over the impact of major changes to peace in Northern Ireland.
Former education secretary Mrs Morgan advised the Government against ignoring the “evidence for peace” in Northern Ireland and undermining business and financial security, with Mr Clarke arguing the UK would suffer “terrible damage” if customs union arrangements were not replicated.
Ripping up existing trade deals could be “deeply damaging” to jobs and communities, Labour’s Yvette Cooper also said as she opened a backbench business debate on customs and borders.
The chairwoman of the Home Affairs Committee warned time was running out for Parliament to “help shape the negotiations” and to hear from the Government about what it is going to do.
The debate was attended by very few pro-Brexit MPs while any vote in favour of the motion, which was moved by 10 select committee chairs, would be non-binding on the Government.
Speaking during the debate, Treasury Select Committee chairwoman Mrs Morgan said: “Professor Patrick Minford, who many members on my side of the benches will say some people should listen to, said very clearly when asked about the free trade agreements and the free trade policy we are currently going to pursue he said, ‘We don’t have any precedents for this’.
“This country has been asked to experiment at other people’s pleasure with a free trade policy where we do not know what the costs will be for constituents and businesses in this country.
“And I say to my party: If we undermine and ignore the evidence for peace in Northern Ireland and we undermine the business and financial security of the people in this country we will not be forgiven for a generation.”
Mr Clarke earlier said former colleagues in the governments of Margaret Thatcher and Sir John Major who now sit as peers all backed the motion, adding: “They are of the same opinion because it is utterly unprecedented for us to get in a position of this kind, I do agree.”
He said it would be “grossly irresponsible” to put a hard border in the middle of Ireland, adding: “What we want is no new barriers. What we want is no customs processes. What we want is the necessary level of regulatory convergence. I think the easy way to do it is to stay in the customs union and stay in the single market.
“If not, we need what the Prime Minister described as a customs partnership – something which looks remarkably like the single market and customs union.
“It would do terrible damage to this country if, for strange ideological reasons in the confused aftermath to a misguided referendum, if we were to take such a foolish step as not to replicate it in any future arrangements we have.”
Independent North Down MP Lady Hermon warned Mrs May over the prospects of a “no-deal” Brexit for the Irish border, telling the debate: “If we have no deal we will inevitably have a hard border in Northern Ireland and we would see the return of violence in Northern Ireland.”
But Labour Brexiteer and former minister Kate Hoey said the EU was “seizing on divisions” in the Commons to pursue demands.
She said: “I do believe that the European Union is actually seizing on divisions on this issue to pursue certain demands which are just not necessary.
“It’s certainly using the Irish border as an issue in terms of the customs union.”