Andrew Scott, lecturer and former Deputy Dean at London Business School, suggested the PM would only have time to negotiate some form of transitional deal with the European Union.
“I don’t think there is enough time in two years to get a future deal done,” he said.
“The best we can do is some form of transitional arrangement. But the UK has to make itself as welcoming as possible to a global world so I find it very hard to see how they won’t a permissible regime for high-skilled labour.”
Prof Scott said it was hard to assess what Brexit would mean for the UK’s future trade as the decision to leave Brussels was a “ big structural shock”.
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Andrew Scott said two years was not enough time to get a deal done
He said: “I think the hardest thing in assessing Brexit is that most of our evidence on trade, we haven’t got anything that says here is a country that used to trade and then suddenly starts to do less.
“Most of the evidence we’ve got are about those opening up, or gradually opening up or gradually tightening.
“We haven’t got such a big structural shock before so there will be quite a lot of uncertainty.”
During a debate in the EU Parliament earlier this month, Brussels decided to take a hardline approach with the UK ahead of exit talks to the fury of pro-Brexit MEPs.
I don’t think there is enough time in two years to get a future deal done
Anders Vistisen, of the Danish People's Party, shredded Brussels’ demands to Theresa May as he took to Facebook to declare his support for the UK.
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He said: “Great Britain should not be punished!!! The EU Parliament has now adopted its position on Brexit… and it has become clear the EU Parliament wants a hard line against Britain.
“They do not want to negotiate a future trade deal with Britain before they have agreed to pay the [Brexit bill], the EU has demanded. [They] have given Spain a veto right in relation to the issue of Gibraltar in the new agreement.
“If the demands set out by the EU Parliament are implemented, it will do irreparable damage to both Britain and the rest of the EU.”
Meanwhile, Swedish politician Mattias Karlsson told Express.co.uk it was “disgusting” that the EU was threatening to stick Britain with a bad deal.
Mr Karlsson, the group leader of the Sweden Democrats in the Swedish Parliament, said: It’s disgusting actually. I think we need Britain – all the European countries need Britain.
“We are cousins in a cultural sense, we have a lot of common interests and the British people have democratically chosen this path to leave the European Union.
“We should respect that and we should make the negotiations as smooth and friendly as possible. The signals that are now coming from the European Union, the leadership there, are just appalling.
“Threatening Britain and making remarks that are not respectful to the British people, I think it’s just sad.”