The event at the Conservative Party conference in Birmingham, central England, saw a softening in tone from some former hardliners in the dispute with the EU, matching a shift from the foreign minister James Cleverly, who is leading talks.
"I understand the complications and maybe we could have understood them a bit better, sooner. But now the mood music certainly seems to be changing and I very much hope that we get some solutions," said Northern Ireland Secretary Chris Heaton-Harris.
"Let's hope we can put the protocol to bed, get the assembly going, and then everyone can move forward in a peaceful and prosperous Northern Ireland."
Both Britain and the EU agreed to the Northern Ireland protocol as a way to avoid reinstating border controls between the British-run province of Northern Ireland and EU member Ireland after Britain left the EU, seen as key to protecting peace on the island.
Heaton-Harris said that the protocol wasn't written to complicate trade between Northern Ireland and Britain, but it had done, and needed to be renegotiated so that unionists would rejoin the devolved Stormont executive.
He added that "discussions reopened with gusto" on the protocol in a call with Cleverly and EU negotiator Maros Sefcovic last week.
Heaton-Harris once co-chaired the European Research Group (ERG) with Steve Baker, a self-styled "hard man of Brexit". Baker organised lawmaker rebellions against Theresa May's deal, pushing for a harder form of Brexit.
Baker said that having acted with "ferocious determination" to get Britain out of the EU, he regretted how that might have damaged relations with the bloc.
"It's with humility that I want to accept and acknowledge that I and others did not always behave in a way which encouraged Ireland and the European Union to trust us," Baker said, adding that both had legitimate interests that Britain was willing to respect.
"I'm sorry about that, because relations with Ireland are not where they should be, and we all need to work extremely hard to improve them."
(Reporting by Alistair Smout; Editing by Frank Jack Daniel)
By Alistair Smout