Tony Blair, who was one of the most prominent campaigners for a second referendum on EU membership, has said he would have backed Boris Johnson’s post-Brexit trade deal with Brussels in the Commons. The former prime minister revealed he would have supported the Labour leader, Keir Starmer, who whipped his MPs to vote in favour of the prime minister’s agreement with the EU last week before the end of the transition period. Starmer – who also backed remain during the 2016 vote as well as calling for a second referendum in 2019 while serving as the shadow Brexit secretary – faced pressure from his own party ranks over his decision to support the deal, despite criticising it as “thin”. Three Labour junior frontbenchers resigned after defying Starmer and refusing to vote for the agreement. They were among 36 of the party’s MPs who abstained. One Labour MP went further and voted against the deal, which sailed through the parliamentary approval process on 30 December. Starmer, who before becoming leader last year accepted that Johnson’s election victory at the end of 2019 “blew away” the case for a second Brexit referendum, had declared Labour’s support for the prime minister’s trade deal with the EU after an agreement was reached on Christmas Eve. Asked if he would have voted for the deal in the Commons, Blair – among the most high-profile members of the remain camp during the 2016 Brexit referendum – told Times Radio on Sunday: “I would have backed the leader on this. I mean, look, it’s a tactical question for the Labour party because the problem is … it’s open to your opponents to say that if you don’t back the deal, then you’re voting for no deal.” He continued: “I would have backed the leader on it. Look, there was a case for abstaining and there was a case for … voting for it because the alternative’s no deal.” He added: “I don’t think it particularly matters to the Labour party either way. I think what does matter is that we’re still in a position where we’re pointing out what the problems with this deal are.” Separately, in a piece published on Sunday, Blair argued that though he was “passionately opposed” to Brexit and that he had not changed his mind about its “wisdom”, it was now “reality” and “we must make the best of it”. Meanwhile, Johnson confirmed he would continue as prime minister after Brexit and sought to play down issues with red tape over trade after the UK formally severed ties with the EU following the end of the transition period at 11pm on Thursday. “Of course, there are going to be changes and we’ve made that clear,” the prime minister told the BBC’s The Andrew Marr Show on Sunday, adding: “Actually, I think there’s a great opportunity for British SMEs [small and medium-sized enterprises] and exporters of all kinds.” He continued: “What we’ve seen is many companies in this country not exporting in the way that they could … the tragic reality of … business life is that there is some bureaucracy. We’re trying to remove it but we have a massive opportunity to expand our horizons and to think globally and to think big.” Asked if he would carry on as prime minister after Brexit, Johnson said: “Yes.” The prime minister added: “We now have freedoms that we haven’t had for 50 years and there are lots of reasons to be very positive about this otherwise grim new year.”