Chris Mason: Dissent fizzes again at the top of the Labour Party

After the spray of resignations, fury and anger a month ago following Labour's calamitous election results, the Makerfield by-election campaign had put a temporary cork in the bottle of the party's dissent.

It turns out we didn't have to wait to find out if the Greater Manchester Mayor Andy Burnham would be returning to Westminster before the bubbles of anxiety about Sir Keir Starmer would be visible again.

The prime minister had sought to seize this brief opportunity to project direction and delivery and saw the Defence Investment Plan, or DIP, as a case study in both.

Instead it has become the latest example - according to his departing ministerial critics - of his inability to get things done.

He has his work cut out now to stop that becoming the epitaph to his premiership.

The DIP, alongside the anticipated imminent announcement about a crackdown on social media access for teenagers, was meant to be one of the weighty announcements that Sir Keir could point to and so draw a contrast between what he was doing in government and what his ambitious wannabe successors were doing at the same time – plotting and schmoozing with Labour MPs.

But now, days before he heads to the G7 summit of world leaders in the south of France, he faces a fresh setback.

Defence Secretary John Healey resigned on Thursday, writing in his letter to Sir Keir that the level of military spending proposed by the prime minister "falls well short" of what's needed to protect the country.