European attitudes to Brexit have hardened in months since vote, experts say

European attitudes towards Brexit have hardened in the six months since the referendum, with support for Britain declining "significantly" because of the approach Theresa May has taken, according to a new report.

The report, by a group of academics working on the UK in a Changing Europe initiative, warns that many in continental Europe regard the UK as "living on Fantasy Island" over its hopes for its new relationship with the EU - something which could lead to a "showdown" following the tabling of Article 50 in March.

A crunch issue is likely to be the "divorce bill" expected to be presented to the UK by the European Commission, which reports suggest could be as much as £50 to £60 billion.

The new report's authors predicted the demand would be "a considerable embarrassment" politically for Theresa May and could result in a court battle which would drag on long after the expected date of UK withdrawal in 2019.

London School of Economics assistant professor Sara Hagemann said that Mrs May's post-referendum tour of EU capitals "seems to have generated little support for the British cause".

The prospect of Brexit has "united the EU27 to a degree rarely seen before", with none of the remaining members ready to agree to an arrangement that looks attractive to eurosceptics in their own countries, she wrote.

"While several of these countries first expressed the hope that a solution would be found to keep London 'closely involved in EU affairs', attitudes are now quite different," said Dr Hagemann.

"The UK Government is seen as working opportunistically with only UK interests in mind and little consideration for wider European issues and priorities.

"Therefore, support for the British has declined significantly even amongst London's erstwhile friends.

"Even Denmark, the UK's 'little brother' which usually follows closely in its footsteps, has made clear that any concessions that do not benefit Copenhagen will simply be rejected.

"The UK Government can take the tone and position of this small and like-minded ally as a signal of what is ahead when actual negotiations begin during 2017."

And Angus Armstrong of the National Institute of Economic and Social Research said there was "little or no evidence that EU member states have moved beyond their reflexive - and understandable - rejection of the UK's desire to 'have its cake and eat it'."

The key moment in the Brexit negotiations is likely not to be Mrs May's tabling of Article 50 - which triggers the two-year period of negotiations - but the EU's response to it, said Dr Armstrong in the new report, entitled Brexit: Six Months On.

"If the continental consensus is that the UK is still living on Fantasy Island, we could be heading for a showdown sooner than anyone expects," he wrote.

The EU response, expected within a few weeks of the invocation of Article 50, is likely to include the "divorce bill" demand to cover UK contributions to the EU seven-year budget, which runs until 2020; existing commitments which will become due for payment in the years to 2023; the UK's share of pensions for EU staff; and guarantees which could be called upon in the future.

LSE professor Iain Begg said: "I suspect that the money issue is going to be far more potent than has been allowed so far.”

"We've heard whisperings of a £50-£60 billion divorce bill coming out of the negotiations.”

"It poses a challenge for the Brits going into the negotiation.”

"(European Commission negotiator Michel) Barnier comes along and says 'Here's a bill for 60 billion euro'. Britain says 'Get lost'. Barnier says 'If you don't pay, we'll sue you'. 'Fine, sue us'. That's the kind of contest it could end up being, which people haven't really envisaged."

Cambridge University EU law professor Catherine Barnard said any legal battle over the size of the payment could finally have to be settled by the International Court of Justice in The Hague, which would take "years and years".

The court case would not necessarily derail the Article 50 talks, but the UK could have to leave the EU without knowing what the final size of the bill was going to be, she predicted.

The UK in a Changing Europe report said the UK Government's response to the Brexit vote had been characterised by "massive shock and apparent inertia", with ministers' refusal to spell out their plans appearing "less like calmness and more like transfixion in the Article 50 headlights".

Based on the few details which ministers have revealed, the authors assess that Mrs May is probably aiming to take Britain out of the single market - and possibly the customs union - and to seek a free trade deal for goods and sectoral agreements to allow as broad as possible access for services. Meanwhile, immigration would be brought "fully" under UK Government control, resulting in a "large fall" in EU migration to the country.

Although the Prime Minister has ruled out European Court of Justice jurisdiction over UK law, she has left open the option of the EFTA Court, which applies the same rulebook to Norway, Iceland and Liechtenstein, the report noted.

The authors judge it possible the UK will continue to make payments into the EU budgets, with Dr Armstrong pointing out that Mrs May's team have "conspicuously and deliberately failed" to rule this out. But the report warns that divisions within the Conservative Party and the Cabinet itself may "hamstring" the Prime Minister as she finalises her position in the weeks before the tabling of Article 50.