The UK will not be able to rejoin the EU under the special conditions it has enjoyed in the past, veterans of Brexit negotiations quoted by the "Guardian" have said.
The warnings came as senior Labour Party politicians, fighting for leadership of their party and country, speak openly about their desire to return to the Union at some point in the future.
Georg Rickelles, a former adviser on the EU's Brexit task force, said he expected member states to take a "very warm, welcoming" position, but also "firm" on a British bid for membership.
"There is a strategic need for the EU and the UK to work together, but I don't think there would be an appetite for opening up new decades of British exceptionalism," he said. "The price of re-entry would be membership under normal conditions.".
During its 47th anniversary of EU membership, Britain achieved an unprecedented special status: giving up key policies such as the single currency and the passport-free Schengen zone, as well as a concession on payments to the EU budget, while establishing itself as an agenda-setting state.
Sandro Gozi, Italy's European Minister from 2014 to 2018, said "we will certainly start" with these standard conditions when asked about eurozone and Schengen membership in any possible re-entry negotiations. "It is clear that the tailor-made policy is over and that the UK's negotiations must cover all the issues that are foreseen for each candidate".
Gozzi - currently an MEP and chair of the European Parliament delegation to the EU-UK Parliamentary Assembly, predicted that EU member states would welcome a British bid to rejoin despite the uncertainty surrounding a possible Nigel Farage prime ministership.
Wes Streeting noted at the weekend that the UK should rejoin the EU in the future. Although allies of the former health secretary say it cannot happen without an election or referendum to get the British electorate's approval, his words have inflamed long-hidden divisions over Europe at the top of the ruling Labour Party.
Andy Burnham, the mayor of Greater Manchester, who is seeking to return to Westminster to challenge the prime minister, has previously said he wants Britain to rejoin the bloc while he is alive. But yesterday he made it clear he would not seek to do so if he became prime minister in the short term.
Gozzi said: "Brexit is a huge disaster for the UK, but it is also a loss for the EU... If, at a time of such huge global turmoil, the UK decides to seek re-join the EU, I think that would be a huge victory for our political model." He stressed that this was not a victory over the UK, but about "our attractiveness".
The UK also has other options, such as "being associated with the single market" and being a founding member of a new European Security Council, a proposed defence leadership body that could include up to a dozen members but has not yet been fully detailed, he added. "I think the options are more than just full accession. But that would depend largely on the UK making a decision, understanding what it wants," Gosi said.
Polish Foreign Minister and Anglophile Radosław Sikorski has also warned Britain not to expect a similar deal to its previous "de facto optional membership" of the EU. Earlier this month, he said British elites should "realise" a fundamental principle of the European Union: that you get more benefits when you share some of your sovereignty.
A future bid by Britain — as a former member that went through a bitter and contentious divorce from the EU — was also seen as something different from all the other cases.
Riqueles, now deputy director at the Center for European Policy, said many in European capitals and Brussels welcomed the "spirit and signals" from Britain, but stressed that this was far from a formal process. "The EU would need to see a lasting national consensus that the UK has truly changed its mind".
Reflecting on his own experience, he noted: "The EU can work with Britain when it knows what it wants. It has a hard time with Britain that wants the benefits of integration while maintaining a policy of division".
"The Brexit world no longer exists," he said, referring to Russian militarism, Chinese economic coercion and Donald Trump's "America First" policy. "I think every sensible person should see that Britain and the EU belong to the same strategic space. If that were the national consensus [for Britain to return to the EU] ... I think the EU would be fully and very seriously engaged. But are we there yet? Not yet.".
European Commission spokeswoman Paula Piño declined to comment on possible terms of negotiations. Referring to the upcoming EU-UK summit, expected to take place in early July, she said: "There are talks about closer cooperation in a number of areas. That is the stage we are at now, and that is what we are working on in preparation for the next summit, rather than speculating on big, new or reopened issues".