Many of Scotland’s highest-profile thinkers have called for Brexit to be called off as "its disastrous consequences become clearer every day".

Scores of senior figures from the worlds of politics, business, academia, and the arts have signed a landmark letter to The Herald breaking a fragile consensus accepting last year's referendum.

Big political names adding their names to the letter include former Labour first minister Henry McLeish; his Liberal Democrat deputy Jim Wallace; SNP MEP Alyn Smith; and former Tory MEP Struan Stevenson.

They are backed by a Who's Who of Scotland's intellectual elite, including historians Sir Tom Devine and Chris Smout; former chief medical officer Sir Harry Burns; scientist and Edinburgh University vice-dean Prof Anne Glover; distinguished international jurist Sir David Edward; businessman and diplomat Lord John Kerr; and trade union leader Grahame Smith.

Their ground-breaking intervention comes amid growing concern at home and abroad that the UK economy is already suffering from crippling uncertainty over its future relationship with its biggest trading partner.

The signatories wrote: "We see our society, economy and politics becoming ever more undermined due to the impact of Brexit.

"We recognise that a narrow majority voted to leave the European Union, but the disastrous consequences are now becoming ever clearer – every day.

"Even before the UK has left the EU, we face falling living standards, rising inflation, slowing growth and lower productivity."

"In a democracy, it is always possible to think again and to choose a different direction.

"We need to think again about Brexit, to have a UK-wide debate about calling a halt to the process and changing our minds."

Today's letter represents a significant challenge to both Labour and the Conservatives at Westminster. The SNP and the Liberal Democrats have both opposed Brexit staunchly, with the latter party calling for a second referendum.

But both Prime Minister Theresa May and Opposition leader Jeremy Corbyn have accepted the result of the Brexit vote even as public and academic doubts grew.

Earlier this month veteran Labour MEP David Martin told The Herald his party should be the vehicle to stop Brexit. Mr Martin has signed today's letter as have former Labour cabinet ministers Helen Liddell and George Robertson and their current fellow peer George Foulkes.

Their signing came after former Prime Minister Tony Blair this weekend suggested it was "possible' that Brexit would not happen. Westminster sources have suggested there are now Conservative ministers who feel the same as negotiations with the EU became a reality.

The first Tory to break ranks on the issue was former MEP Struan Stevenson, who last week in The Herald revealed his desire for a rethink amid evidence leaving the European Union will put up barriers to Scottish farm exports while a potential US trade deal opens up Scotland to imports of cheap, low-quality American beef and chicken.

English academics this week warned Brexit marked a serious threat to Britain's food security with 80 per cent of vegetables and 40 per cent of fruit being imported.

Tim Lang of City University, described the situation as a "serious policy failure on an unprecedented scale".

His concerns over food security echo those of Professor David Bell of Stirling University and Scottish farming experts who warned of similar problems earlier this summer.

Prof Bell is one of several academic experts on the EU, its laws and economic impact,to sign today's letter. Others include Kirsty Hughes of the Scottish Centre on European Relations; and Professors Jo Shaw, Andrew Scott and Christina Boswell of Edinburgh University.

Forecasters, meanwhile, predict stunted growth for Scotland and the rest of the UK even ahead of a final deal.

Accountancy firm PwC attributed a low growth prediction to "slower consumer spending growth and the drag on business investment from ongoing political and economic uncertainty relating to the outcome of the Brexit negotiations".

A spokeswoman for the Department for Exiting the European Union was unmoved by the Herald letter.

She said: "In one of the biggest democratic exercises in our history, the British people voted to leave the European Union.

"The Government is committed to delivering on that mandate, by building a new deep and special partnership with our closest allies and neighbours in Europe."