He triggered Brexit. Now Lord Cameron warns Burnham against rejoining EU

Former prime minister David Cameron has advised Andy Burnham against starting a "decade-long debate" over whether to rejoin the European Union.

Lord Cameron, who left Downing Street after calling the 2016 referendum and leading the remain campaign, said starting a conversation about rejoining the EU would be "very long and painful".

Mr Burnham has reignited discussion regarding Britain’s future relationship with the EU. He is due to meet EU leaders in Brussels next week to sign agreements he claims could boost GDP by 0.4% – covering agriculture, emissions trading and a youth mobility scheme.

Following the summit, the UK will "explore options" for a different long-term relationship with the bloc.

His recent remarks have raised questions about the UK returning to the EU or adopting freedom of movement rules, though the Prime Minister insisted voters would be "the boss" of changes.

Lord Cameron told Bloomberg he was "desperately disappointed" when the UK voted to leave the EU 10 years ago, but he warned against attempting to reverse the decision.

"Instead of launching an argument about rejoining, which I think would be a very long and painful argument – and who knows where it would end up – instead of that, focus on how do we be the best friend, best neighbour, best partner," he said.

He said "flirting with rejoining" could hamper efforts to get a better deal, because EU countries might feel there is no point if the UK rejoins anyway.

"If you’re not going to, you know, commit to trying to make the partnership stronger because you’re flirting with rejoining, I think there’s some dangers there," he said.

He appeared lukewarm on rejoining a customs union, saying economic problems are not down to Brexit.

"Our economic problems are we are overspending, over-borrowing, over-taxing, over-regulated, and far too much being spent on working age welfare. Those are a set of problems that have nothing to do with Brexit," he said.

"Do we really want to go into another decade-long debate about whether we should be in or out, when actually we should deal with our own problems while making the partnership model work?"

The EU’s former chief Brexit negotiator Michel Barnier recently warned of trade-offs for deeper ties, stating there will be "no cherry picking".