Irish hopes of avoiding a "hard border" with the North after Brexit centre on the EU conceding a special case for treating the entire island as a single unit, EU Commissioner Phil Hogan has said.
And he signalled that the future of the peace process is central to Ireland's case in Brexit negotiations which are due to start in late March.
Mr Hogan is scathingly critical of Britain's conduct on Brexit since the outcome of the referendum on June 23.
"Clearly, Brexit is a mess and getting messier," he said.
But Mr Hogan said he hoped the EU may be able to persuade the London government on a common position for the entire island of Ireland. This would ensure the freedom of goods and people on the island and avoid a border for customs or immigration.
He said the EU has "invested heavily" in the peace process, with a total of €3.5bn in cross-border and special "peace grants" since the first IRA ceasefire in 1994 - therefore Brussels will want to safeguard it.
"The European Commission has a vested interest in protecting the Good Friday Agreement and the success it has been in bringing peace to the island of Ireland since 1998," he said.
However, there are concerns among EU diplomats that Ireland has not done enough to win over the EU's chief negotiator, Michel Barnier.
And there are fears the Taoiseach's repeated references to "democratically elected EU governments" making all key decisions have caused alarm.
But Mr Hogan insisted that his former colleagues in Government have done all they can so far to push Ireland's case and are hamstrung by London's failure to spell out its concerns ahead of full Brexit negotiations.
"It is very difficult for Ireland to act until they know the UK position, which must be revealed as soon as possible," he said.
Mr Hogan said the abrupt departure of Britain's EU ambassador, Ivan Rogers, showed the British disarray.
"What they need handling negotiations is not people who believe in Brexit, but people who know the lie of the land in Brussels, and who appreciate the risks involved," he insisted.
He warned that if the UK leaves the EU Single Market then "a hard border" with the North, involving potential identity controls and customs tariffs, looked inevitable.
Recent comments by Brexit Minister David Davis, that London may consider payments to the EU Single Market, were encouraging but these had been contradicted by his colleagues Liam Fox and Boris Johnson.
"That is a further example of serious disarray in London on the entire issue," he said.
Mr Hogan said that for Britain to maintain EU trade advantages, there must be "some give" on the issue of migration controls.
He said that the UK has, via the EU, a presence in 53 separate markets, and doing new trade deals for these would be complex and time-consuming.
"India, for example, has already cited greater access to Britain for its citizens as a condition in any new trade deal.
"British voters were sold a pig in a poke on Brexit - nothing is as simple as it looks," the commissioner said.
Mr Hogan also said the timing of the opening of Brexit talks in March, soon after Dutch elections, in the teeth of French presidential elections, and a building federal election campaign in Germany, is not helpful.
"It will make things harder for Britain to negotiate at a time when other member state governments will conclude it is not in their interests to concede membership benefits without the obligations," he said.
Mr Hogan has been out of Irish politics since autumn 2014 and insists he is loath to comment on domestic issues.
On water charges, which he introduced as Environment Minister, he just pointed to the comments of the EU Environment Commissioner, Karmenu Vella, who insists the charges are required by EU law.
On the instability of the current minority coalition, Mr Hogan noted that voters were warned about those dangers.
"But we must respect the people's choice and I hope that in the longer term it will lead to a new kind of politics and a more mature polity," he said.