Labour pitched an alternative vision of Brexit to the EU on Thursday during nearly two-and-half hours of talks with Michel Barnier and his deputy negotiators, which pointed the way for potential compromise on access to the single market.

Jeremy Corbyn’s private session at the European commission headquarters in Brussels lasted almost half as long as the British government has spent in formal negotiations in total since triggering article 50 in March, but went further by also including discussion of Britain’s future relationship.

“They wanted to hear what our overall approach is and to let us know what their overall approach is, not only for article 50 but also for transitional and final arrangements,” the shadow Brexit secretary, Sir Keir Starmer, told the Guardian.

“It was an opportunity for us to have a pretty frank exchange of positions and an opportunity to dive into some of the issues that arise out of that. Hopefully, it is the first of a number of meetings, so we will be able to continue that process.”

Barnier and Corbyn deny that their talks amount to parallel negotiations or undermine formal government talks due to start again on Monday, but officials concede such backchannels have grown in importance since Britain’s inconclusive general election. The EU team also met the Scottish first minister, Nicola Sturgeon, the Welsh first minister, Carwyn Jones, and a cross-party delegation from the House of Lords.

To mark the beginning of the talks, Corbyn gave the Frenchman a copy of the Labour party’s manifesto and an Arsenal shirt with Barnier’s name printed on the back. An EU aide later said the shirt was an appropriate gift for someone committed to fair play on Brexit, who is also a sport fan. In return, the Labour leader received a vintage railway poster from Barnier’s home region of the Savoie Alps, a nod to Corbyn’s perceived enthusiasm for trains.

Corbyn told reporters that the two sides were “not negotiating” as he emerged from the Berlaymont headquarters building at the end of a day that also included meetings with Jean-Claude Juncker’s deputy, Frans Timmermans, and the UK ambassador, Sir Tim Barrow. “We are forming an opinion of what the EU wants in this and representing the views of people that voted for us, particularly about the future of jobs in the UK,” Corbyn said.

“We had a frank discussion about the process and the situation. We have come out of the meeting very well informed about his methods and his process and we have been able to inform him about our respect for the result of the referendum, our wish to maintain and defend jobs in Britain and have an effective economic relationship with Europe in future.”

Labour figures said the key point of difference with the Tories was their ability to convince EU leaders that Britain would not undercut European employment standards, taxation and market regulation once it left – something that may help ease deadlock over other single market rules.

“They are clear that regulatory alignment is really important and that is an issue that has got to be addressed if we are to have a meaningful relationship,” said Starmer. “They are clear about the dangers of free trade agreements that don’t have the sort of frameworks around them that they would expect.”

The Labour leader made his pitch over lunch on the 13th floor of the Berlaymont building – the same dining area where Barnier hosted David Davis on the first day of negotiations last month.

After the day of meetings, Barnier tweeted he had had “good meetings” with Corbyn, Sturgeon and Jones, adding: “My door is open, listen to all Brexit views.” A commission official declined to comment on how Corbyn’s ideas had been received.

The broad theme of Labour’s stance on worker protection is likely to have been welcomed by Barnier, a centre-right politician, who has repeatedly warned that a race to the bottom would make it harder for the EU to strike a post Brexit free-trade deal with the UK.

Labour argues that by being more flexible on legal issues such as citizens’ rights and the European court of justice, it would be able to extract greater concessions than the more hardline government approach. But it is also dropping hints about its growing openness to a softer economic Brexit, too.

“If you say upfront that we won’t be in the Customs Union without having a discussion about what possibilities there are around the edges of that, then you make it more difficult,” said Starmer. “That’s why we’ve said to government: reset the approach.”

In a naked appeal to splits among Conservatives, the Labour team that emerged from the Berlaymont claimed to reflect growing voices of the dissent in the UK Treasury.

“Chancellor Philip Hammond [is] adopting language very close to ours,” said Starmer. “We say putting jobs and the economy first; he says putting jobs and prosperity first. We say no over the cliff; he says transitional measures. We say no arbitrary cap on immigration and he says don’t cut off migration.”

This article was written by Dan Roberts and Jennifer Rankin in Brussels, for The Guardian on Thursday 13th July 2017 18.21 Europe/London © Guardian News and Media Limited 2010