Mary Lou McDonald has said that Boris Johnson’s government had not been “upfront” with unionism, and had been determined to act “in a unilateral fashion”.
The Sinn Fein president also said she had found Mr Johnson’s tenure as British prime minister difficult and frustrating, adding that there was a tendency to act “outside of good faith”.
Ms McDonald was speaking in a pre-recorded interview for ITV show Peston as the former Tory leader voted against a key element of the latest EU-UK deal on the protocol.
The Windsor Framework was unveiled by UK Prime Minister Rishi Sunak and European Commission president Ursula von der Leyen last month, and hailed as a significant breakthrough in outstanding problems with post-Brexit trade in Northern Ireland.
I think also there was an absolute determination to act in a unilateral fashion, to act outside of good faith— Mary Lou McDonald, Sinn Fein president
On Wednesday, Mr Johnson and members of the DUP were among the 29 MPs to vote against the Stormont brake aspect of the deal, with 515 voting in favour of it.
Mr Johnson, who agreed to the original protocol with Brussels as a way of avoiding a hard border on the island of Ireland, said he would find the deal difficult to accept if aspects of EU law remained in place in Northern Ireland.
DUP leader Sir Jeffrey Donaldson said the “bottom line” for the party to restore Northern Ireland’s powersharing institutions was an assurance that EU law could not impede Northern Ireland’s ability to trade with the rest of the UK.
“Until that is resolved, I can’t commit to the Government that we will restore the political institutions – it’s what I want to do, but we need to get this right,” he said.
When asked about the difference in tone since Mr Sunak took office, Ms McDonald said that he appears to be pursuing a more stable relationship with the EU.
“Boris Johnson, if perchance he watches this programme, will not be surprised to hear me say that I found those times very, very difficult, very, very frustrating.
“I think the Johnson administration was not at all upfront with unionism, with Irish unionism, which was a problem for all of us.
“And I think also there was an absolute determination to act in a unilateral fashion, to act outside of good faith.
“And I can only hope, and I suppose time will tell whether or not the new Prime Minister will in a consistent way observe international law, act in partnership with others, and rebuild the necessary, healthy dynamic relationships between Ireland and Britain – but also with our European partners.”
Ms McDonald said there was still “substantial grounds for optimism” on a breakthrough that would see the return of powersharing institutions, adding that it was “a case of full steam ahead” on the Windsor Framework.
“I noted Jeffrey Donaldson’s comments today… he has a position that at this stage a return to Stormont is not possible. I disagree with him on that point.”
Ms McDonald said that at a time when the eyes of the world would be on Northern Ireland for the 25th anniversary of the Good Friday Agreement, there was “an immediacy around grasping the opportunities as they present”.
When asked about a potential referendum on Irish unity, Ms McDonald said the party wants “everybody involved” in discussions that would precede such a vote.
“I believe in the course of this decade that we will have the referendums,” she said.
“I want to commence and deepen the preparation work, where we have an all-of-society conversation around what Ireland will look like in the next 10 years, the next 20 years, the next 25 years, and we want to have everybody involved in that.
“But I believe absolutely that we will have the referendums, I believe absolutely that we can win those referendums and I believe that we can build an incredible new democratic dispensation on this island.”
She also said the party is “open” to discussions on reforming aspects of the Good Friday Agreement.
“So we’re open to any and all of those conversations, mindful only of the absolute need to preserve and protect the essentials of the Good Friday Agreement and of powersharing – the essentials of parity of esteem, equality.
“And then of course parity of protections for minority rights. Those really are at the heart of the Good Friday Agreement.”