Green fears agricultural subsidy wars in a post-Brexit Britain

devolution settlements were created while we were a member of the EU and when they were being written, none of the various governments, which wrote them thought: ‘Well, what happens if?’ There is just no provision in the devolution settlements for leaving the EU.

“We must ensure the benefits of free trade around the UK, which we’ve all taken for granted, because we are one country, are preserved after Brexit because a lot of the rules about trade have been operated at a European level rather than at a UK level.”

He added: “Agriculture is clearly an area where most of the rules were set at European level but those that weren’t are devolved down and we want to continue that.

“We need to make sure that we don’t have subsidy wars to try to help sheep farmers, some in Scotland and some in Wales and so on.”

Last year, UK farmers received £2.8 billion in EU subsidies, with Scottish ones getting £423 million, more than 15 per cent – much more than Scotland’s general population share of nine per cent.

While the UK Government has pledged to continue the current system of subsidy to 2020, there are no details about how it would work thereafter.

Over the summer, Michael Gove, the Environment Secretary, spoke of creating a “green Brexit,” whereby farm subsidies would have to be earned rather than merely handed out with pay-outs contingent on farmers agreeing to protect the environment.

The Scottish and Welsh governments have said unless Mrs May changes her flagship EU Withdrawal Bill, then they could not recommend Holyrood and Cardiff Bay giving their consent. They believe Whitehall is intent on a power-grab.

But while Mr Green and his colleagues have insisted they will give both nations more powers post-Brexit, they want first to ensure UK-wide frameworks are in place.

A spokesman for Michael Russell, the Scottish Government’s Brexit minister, said: “Devolved powers currently operated at EU level must be returned to Edinburgh, not Westminster, in line with what people across Scotland voted for in the 1997 referendum.

“We are not opposed in principle to common UK-wide frameworks but that must be by mutual agreement and not by imposition. As they stand, the UK Government’s proposals are a blatant power-grab and we cannot recommend that the Scottish Parliament gives its consent,” he added.

In Brussels, Mr Juncker unveiled his personal vision of a stronger, more united and more democratic Europe.

He spelled out closer ties on currency, banking, borders and defence across the 27 states after Britain had left. “Ten years since crisis struck, Europe’s economy is finally bouncing back and with it our confidence,” he said.