Britain's Brexit minister has pledged to "get down to work" as he kicks off a first full round of negotiations but a year after Britons voted narrowly to leave the EU their government seems at war with itself over the divorce.
Her authority diminished after losing her majority in a June election she did not need to call, Prime Minister Theresa May has struggled to control rival cabinet ministers, worrying European Union negotiators who stress that 20 months until Brexit is very little time to negotiate an orderly departure.
"It's time to get down to work and make this a successful negotiation," veteran anti-EU campaigner David Davis said as he was welcomed by chief negotiator Michel Barnier before their teams began four days of talks.
In London, media were rife with reports of infighting echoing the Leave-Remain rifts that May's Conservative party suffered during the EU referendum. Her spokesman said she would tell ministers not to reveal cabinet discussions.
Foreign Secretary Boris Johnson, in Brussels for a separate meeting, passed up a chance to deny that ministers are at odds.
His backing helped secure a four-point victory for the Leave camp in June last year.
Asked point blank if the cabinet was still "split on Brexit", Johnson simply said he was pleased negotiations had begun and then defended the offer May has made to protect the rights of EU citizens in Britain.
Finance minister Philip Hammond, who like May campaigned last year to keep Britain in the EU, accused unnamed colleagues of trying to undermine what is seen as his push for a "soft Brexit" that prioritises trade rather than hardliners' demands for controls on EU immigration or an end to EU legal oversight.
Splits in London over basic issues, such as the need for a phased withdrawal lasting for some years, could raise the risk of a failure to reach any deal, EU officials say.
That would raise huge uncertainty for businesses and millions of people across Europe as Britain would simply be out of the bloc on March 30, 2019 with no clear rules on what that should mean.
London and Brussels have taken initial negotiating positions saying they are ready for such an outcome.
But most officials in Brussels believe Britain, for one, must be bluffing, since the legal limbo into which it would be pitched would be so damaging.
However Gus O'Donnell, Britain's former top civil servant, said the chances of a smooth Brexit were at risk.
"It appears that cabinet members haven't yet finished negotiating with each other, never mind the EU," he said.
British businesses are anxious to see a coherent approach in government to indicate early on how a transition would work and how long it would run to help them make investment decisions.
A weekend of media briefings from competing factions within the Conservatives did little to reassure companies, though most cabinet ministers appear now to accept there needs to be a transition, or what May calls an "implementation phase".
In Brussels, Davis acknowledged it was "incredibly important" to make progress, "that we negotiate through this and identify the differences so we can deal with them and identify the similarities so we can reinforce them".