LONDON (Reuters) – Britain urgently needs a national debate on halting Brexit because it threatens economic prosperity and political stability, a group of prominent Scots said in one of the most overt appeals yet to overturn the 2016 referendum result.

In a letter published on the Financial Times website on Tuesday, the group said the vote to leave the European Union had already caused much damage to Britain’s international standing and prompted some EU citizens living here to leave.

“Even before the UK has left the EU, we face falling living standards, rising inflation, slowing growth and lower productivity,” said the letter, whose signatories include John Kerr, a former diplomat who devised the Article 50 of the EU’s Lisbon Treaty which allows Britain to leave the bloc.

“We call for a national debate on Brexit. We ask our fellow citizens, and our politicians, to think again. It is time to call a halt to Brexit,” the letter said.

Among the dozens of signatories were historian Tom Devine, poet Christine De Luca, academics, lawyers and former politicians, though they did not include the heads of any major businesses or prominent current politicians.

Britons voted by 52 percent to 48 percent to leave the EU in a June 23, 2016 referendum that exposed deep regional and social divisions. While voters in England and Wales backed ‘Leave’, a majority in Scotland and Northern Ireland voted to remain in the EU, adding to strains between the constituent nations of the U.K.

British Prime Minister Theresa May, a supporter of EU membership who won power in the turmoil following the shock referendum result, has vowed to implement Brexit, though her strategy is the subject of public debate by her own ministers.

While both May’s Conservatives and the opposition Labour Party now explicitly support leaving the club the United Kingdom joined in 1973, some of the Union’s most powerful politicians have raised the possibility of Britain cancelling Brexit.

Former prime minister Tony Blair suggested on Saturday that Britain could end up staying in the EU because public opinion could change.

Brexiteers fear a sharp economic contraction could prompt calls for a second referendum, though they have warned such a step would prompt a major constitutional crisis.

In their letter the opponents of Brexit said it would be much less damaging to reverse course than to press ahead with the complex and divisive divorce negotiations. Britain is currently scheduled to leave the EU in March 2019.

“In a democracy, it is always possible to think again and to choose a different direction,” they said.