London Mayor Sadiq Khan has urged Prime Minister Andy Burnham to begin immediately making the case for much closer ties with the EU, rather than merely promising to consider rejoining in a future election manifesto. Khan proposed returning to the customs union, seeking associate membership and eventually rejoining the EU, arguing that Labour needed to prepare public opinion well in advance.

His intervention contrasts with Business Secretary Jonathan Reynolds, who warned that reopening the Brexit debate could create political uncertainty and economic costs. Reynolds supports improving relations within the Government’s existing red lines, which exclude rejoining the single market or customs union, while former prime minister Tony Blair has also called for considering EU membership over the next decade.