More than 30 leading public figures in the Czech Republic have signed an open letter urging the UK to vote to stay in the EU in next month's referendum.
The letter says the UK plays a key "balancing role" in European politics and a British exit from the EU "would be disastrous".
It is addressed to the Czech-born British playwright, Sir Tom Stoppard.
The signatories include Cold War-era dissidents, supermodel Eva Herzigova and renowned conductor Jiri Belohlavek.
The list is topped by Michael Zantovsky, a former Czech ambassador to London who was spokesman for the late Vaclav Havel, the man who led the 1989 Velvet Revolution that swept the Soviet-backed communists from power. Mr Zantovsky now runs the Vaclav Havel library.
Havel's brother Ivan is also a signatory, as are Cardinal Dominik Duka, Archbishop of Prague, and former gymnast Vera Caslavska, who won seven Olympic gold medals.
The Czech letter speaks of the close historical ties that bind Britain to Bohemia, a common Celtic heritage, medieval royal marriages and the Czechoslovak fighter pilots who served in the RAF in the Battle of Britain.
"Britain... has played a balancing role in European politics, effectively preventing any large European power from playing a hegemonistic role," the letter says.
But it also acknowledges that "many Europeans, in the East and in the West, are frustrated with the decreasing ability of the EU to cope with the current problems".
It says Brexit would leave the UK isolated, "stranded in the middle of the Atlantic", and argues that Europe has gained from the British "democratic institutions, entrepreneurial spirit, common sense and pragmatic approach".
However, the signatories stress that the plea to the UK is non-political - and only one of them is a serving politician.
The Czech Republic and three of its ex-communist neighbours - Hungary, Poland and Slovakia - are in dispute with their EU partners over refugee policy.
The four - together called the Visegrad Group - object to a European Union plan to distribute refugees more fairly across the EU. The four argue that they are ill-suited to integrate migrants, especially Muslims from outside Europe.
There is also a strong strain of Euroscepticism in Czech society - and support for EU membership amongst the Czechs has plunged in recent years.
Some Czech leaders, including President Milos Zeman, have spoken out against other EU policies, besides migration.
Mr Zeman says the EU should lift its sanctions on Russia, imposed over the March 2014 Russian annexation of Crimea, internationally recognised as part of Ukraine.
His predecessor Vaclav Klaus was staunchly Eurosceptic, arguing that the behaviour of EU officials reminded him of the Soviet bloc.