Like it was in the last three rounds of talks, the Ireland border issue is the silver lining of Brexit negotiations.

Hailing the discussions on this issue as constructive, Davis told reporters: "We have made progress in some areas."

"Both sides recognize that the unique situation and the special circumstances on the island of Ireland must fully inform any solutions. Specifically, this week, we have begun drafting joint principles on preserving the common travel area and associated rights," said Davis, "The joint work which we agreed in the August negotiating round on preserving the North-South cooperation strand is moving along at pace."

Echoing his British counterpart, Barnier admitted that "we made progress in some areas."

"Any solution will need to be fully informed by the special circumstances on the island of Ireland and, as I mentioned several times, such solutions must respect both the integrity of the Union's legal order, and the Good Friday Agreement in all its parts," said Barnier.

"I hope that the new dynamic created by Prime Minister May's speech in Florence will continue to inform our work," he added.

The long-awaited Brexit talks launched on June 19, nearly one year after Britain voted to leave the bloc by a narrow margin on June 23, 2016.

May sent a notification letter to the EU in late March, triggering a two-year countdown to Britain's withdrawal of the bloc after more than 44 years of membership.