Last month’s second round of discussions on extricating Britain from the European Union produced a “significant step forward” on the thorny issue of citizens’ rights, even though the talks were at times tricky, Brexit Secretary David Davis said.

In the July 17-20 talks in Brussels, negotiators focused on discussing the rights of EU citizens in Britain and those of Britons in other EU nations after the divorce. Their dialogue produced “four days of difficult, but ultimately productive, discussions,” Davis said in a letter to the House of Lords EU Committee published Wednesday.

“We have taken a significant step forward,” Davis wrote. “There is a much clearer understanding on the detail of the positions on both sides and significant convergence on the key issues that really matter to citizens.”

Davis’s optimism belies cabinet squabbles suggesting that Prime Minister Theresa May’s team is far from unified on its Brexit strategy. It’s also in contrast to the image presented by Davis’s own former chief of staff, James Chapman, who tweeted late on Tuesday that Brexit is a “catastrophe.”

Biggest Calamity

“It’s the biggest calamity for our country since WW2, I’m afraid,” he wrote in the ensuing thread. “I worked for a year trying to make the wretched thing work.”

Chapman, a former political editor at the anti-EU Daily Mail, worked for Davis for a year, leaving his office shortly before June’s general election. Before that, he served as an adviser to then Chancellor of the Exchequer George Osborne during the Brexit referendum campaign—with Osborne the most vociferous campaigner for a “Remain” vote. Davis’s Department for Exiting the European Union declined to comment on Chapman’s tweets.

The discussions on citizens’ rights were “constructive and substantive,” Davis said, pointing to a “significant alignment” in EU and British positions on the issue. Nevertheless, he also flagged up differences of opinion on voting rights after Brexit, the cut-off date before which EU citizens must arrive in Britain in order to benefit from agreed rights after the divorce, and the rights of their family members to move to the U.K.

EU lead negotiator Michel Barnier has said Britain can’t progress to talking about its future trade relationship with the EU until sufficient progress is made on resolving citizen’s rights, the border with Ireland, and Britain’s exit payment. Davis maintained that exit talks and discussions on the future relationship should be held in parallel, as they feed into each other.

“All in all, the second round of negotiations have given us a lot to be positive about,” Davis wrote. “They have, however, only served to reinforce my view that we cannot negotiate the U.K.’s exit properly without addressing what our future relationship looks like.”

At the next round of discussions, scheduled for the end of August, “we shall consider the issues of mutual recognition of professional qualifications and economic rights,” Davis wrote. “We shall also deepen our technical analysis of the social security provisions.” More detailed discussions will also be held on the border with Ireland, he said.