"The referendum campaign was about identity politics rather than about policy," the former Taoiseach tells Newstalk
Former Taoiseach John Bruton believes that the British public should be offered another vote on Brexit.
Speaking to Newstalk Breakfast, Bruton said they made a "major mistake" in deciding to leave the European Union last June.
The veteran Fine Gael politician argued that voters across the Irish Sea didn't know what they were agreeing to and should be allowed hold another referendum where the implications are properly explained.
His comments follow the sudden resignation of the UK's EU Ambassador, who criticised his government's "muddled" exit strategy.
"We need to explain to the British public what leaving the European Union could mean, what leaving the European Convention on Human Rights could mean. Not just for Northern Ireland and the Irish border, but also for Britain itself. The referendum campaign was about identity politics rather than about policy."
Bruton pointed to Ivan Rogers' resignation as having "crystallised how little we know" about the process and implications of a UK departure.
"I think the problem is that the UK government, having decided to have a referendum offering the option to the people of leaving the European Union, doesn't yet know what terms it wants to look for, for Britain's relationship with the European Union once it has left.
"Is it to be an association agreement, is it to be an agreement like that of Norway, or is it to be part of a customs union?
"It hasn't made a choice between those options and as a result, officials representing Britain have no clear guidance and this makes life difficult for them."
He warned that a hard Brexit would be "very difficult" for Ireland and that it was "increasingly inevitable as British Prime Minister Theresa May failed to rein in Conservative Party members who are attacking and dismissing "all the softer options" in London.
"If there is a sort of full-speed train crash in the relationship between Britain and the European Union, some of the wagons will fall on us."
Specifically, he believes Northern Ireland would take a hit:
"If a soft Brexit disappears from the agenda and a hard Brexit comes in, then we would have unfortunately to reintroduce customs posts and other controls on the border, which would be very serious."
"The Good Friday Agreement is based on the European Convention on Human Rights and if the UK tries to withdraw Northern Ireland from the European Convention on Human Rights, that will undermine the international agreement with very serious consequences, both for Northern Ireland and Anglo-Irish relations."
While he called on the Irish State to make an effort to explain the situation to the British public, he admitted the island of Ireland was "not very high" on the UK's list of priorities.
"This is all about England looking at itself in the mirror," he said, "rather than looking at its relationship with the rest of the world in a serious, realistic and constructive way."
Bruton agreed with Rogers' assessment that the Brexit process would take a decade, while dismissing Nigel Farage's fresh claims that it could spark desire for an 'Irexit', saying that the Irish people are "supportive of the political project, which is the building of structural peace in Europe and using economics as a tool to build structural peace in Europe."
"Unfortunately the UK never saw it like that," he said. "They saw it simply as a commercial transaction."
"Ireland is very pragmatic about these matters," Bruton concluded. "We don't believe everything in the European Union is perfect, we want to make the European Union better. But we don't want to leave it and we don't want to damage it."