Ulrike Guérot, founder and director of the European Democracy Lab – a European Union think tank – launched the blistering attack on the UK saying Britons must accept that they can’t have “everything both ways”.
The German political scientist urged Britain to admit it has made a “huge mistake” in its decision to unshackle itself from the bureaucratic Union, as the nation was “indulged” by the EU when it was part of the bloc.
Writing for politics website Politico.co.uk, Ms Guérot said: “Yes, we indulged you while you were part of the European Union.
“We gave you your rebate. We allowed you to sit on the sidelines of Schengen and the euro. But those days are over, now that you’ve decided to go.
“It’s time for you to stop acting like a spoiled child and accept that you can’t have everything both ways – departure from the EU but membership in programmes like Galileo and Erasmus; an Irish border that’s both closed but somehow open; access to the single market without its most important conditions; the freedom of movement and no oversight by the European Court of Justice; your pick of the European cherry tree, without bothering to water the soil or tend to its branches.”
Ms Guérot said Britain has showed signs the electorate knows a huge mistake was made in the voted to leave.
She said: “So please, eat your Brexit cake and go. But keep your sticky fingers off our slice of the pie.
“Or better yet, stiffen your famous upper lip and admit you made a huge mistake.
“Deep in your heart, you know that would be the right thing to do.
“If not, why are so many Brits hunting for European passports – German, Spanish, Irish, Maltese, whatever they can get? Why are your youngsters leaving?
“Why is Brexit tearing families apart, making it impossible for parents and children, brothers and sisters to share a happy meal?”
Ms Guérot said there was “still time to reconsider the supposedly ‘inevitable’ Brexit, which nobody over there seems to have any idea how to make work anyway”.
Warning that Brexit will cause a “lot of unnecessary damage on continental Europe”, she said: “Isn’t it time to realise that you too are citizens of Europe, as you agreed to be under the Maastricht treaty, and that when it comes to decisions with such far-reaching implications, we should all make them together?
“So, if Brexit is starting to look like a mistake (and, well, that’s exactly what it looks like), it’s not too late to rethink your decision.”
Ms Guérot promised Britain if it was to decide to “come back” to the Brussels club, it would be reformed into a “democratic and social Europe, so that nobody needs to leave it anymore”.
She added: “Stop trying to have everything both ways. Fight it out among yourselves. Figure out what exactly it is you want.
“And then, well, you just might find, you get what you need.”