Aiming to strike sector-by-sector trade deals with the EU after Brexit could take almost 25 years and damage many sectors of the UK economy, a new report has warned.
According to research from the Centre for Economics and Business Research (CEBR), there are "considerable linkages" between the UK's sectors, and uncertainty over trade deals could block investment and damage the economy.
Former deputy prime minister Nick Clegg will join Conservative ex-minister Anna Soubry and Labour MP Chuka Umunna to present the findings of the research as part of their campaign for the UK to stay in the single market.
The CEBR report, which was commissioned by the Open Britain campaign, said: "A sector-by-sector approach, which seeks to prioritise or choose 'winners' in isolation of others...cannot be achieved without the risk of creating 'losers' through reduced access and reduced future mutual benefits."
The research also warned that the fast-growing "flat white economy" of creative and tech businesses would suffer a "body blow" if curbs on EU immigration are introduced.
At an event in London, Mr Clegg will say: "It is the height of irony that free-market Brexiteers often claim European regulations are the product of an overbearing European super-state, when in fact EU regulations are designed to liberalise markets.
"It is ironic too that arguing to leave the single market on the basis of reducing the regulatory burden we face would in fact lead to reduced trade due to an increase in regulatory trade barriers."
Mr Umunna will add: "The benefits we have within the single market cannot be replicated outside it without cost, since every alternative inevitably means increased barriers to trade.
"It would be an honest position to say this cost is worth paying for severe immigration controls or regulatory freedom or another reason to leave the EU."
Ms Soubry will also present the report as a "challenge" to those who back leaving the single market, and insist that "there is no mandate for one particular Brexit option".