“DECISIONS, detail and delivery” on key Brexit issues are required from the UK Government, and evidence suggests a “deep relationship with the single market” should be retained, a business leader will declare today.

Paul Drechsler, president of the Confederation of British Industry, is expected to tell CBI Scotland’s annual lunch in Edinburgh that evidence must be put before ideology to protect Scottish companies and jobs as the UK leaves the European Union.

He is also expected to advocate an “open approach to migration”. He will also voice support for a customs union unless or until an alternative is ready and workable.

According to an advance text of his speech, Mr Drechsler will say: “We must prioritise our relationship with the EU – 48 per cent of UK export goods go to the EU and 78% of UK exporters sell into the EU.

“Protecting that trade has to be our number one priority. Even if we signed free trade agreements with the USA, Canada, Australia and New Zealand tomorrow, it would account for less than 3% of our total trade in goods and services. To do the same with Brazil, Russia, India and China would achieve even less - just 2%.”

Mr Drechsler will add: “The evidence says we can do both - trade with the EU and with the rest of the world. Germany already does 4.7 times more trade with China than we do, without a free trade deal and from within a customs union. We don’t need to cast aside established EU partners for potential riches beyond… If we lose access to the single market, it could reduce UK trade by up to 30%.”

He will call for an immigration system which “gives Scotland the flexibility it needs, and sends a clear message that Britain is open for business”.