Just over a week ago, Emily Thornberry, Seumas Milne and Damian McBride were spotted having dinner at Browns in Covent Garden. The purpose of that meeting has now become clear: McBride is back. Gordon Brown's former aide has been appointed as Thornberry's political adviser. Having been outside of Westminster since resigning in 2009 over the "smeargate" emails, McBride has returned to manage the fraught politics of Labour's defence review.

Though some never forgave him for the scandal, he was regarded by journalists and MPs as one of the party's sharpest operators. McBride is on a fixed-term contract and is due to work for Thornberry until the party's annual conference this autumn. His appointment follows the shadow defence secretary's gruelling appearance before the Parliamentary Labour Party last week. "There's no point in trying to shout me down," she was forced to declare at one point. A shadow minister told me afterwards: "Emily just evidently hadn't put in the work required to be able to credibly address the PLP - totally humiliated. Not by the noise of the hecklers but by the silence of any defenders, no one speaking up for her."

McBride shares Jeremy Corbyn's opposition to Trident renewal but has also been sharply critical of his leadership. "I agree with Corbyn on Trident, Syria, HS2, austerity and any number of other issues," he wrote in the Times on 6 January. "But I have concluded that he is incapable of persuading a single non-Labour voter to do the same, not as long as he persists in his obsession with internal battles." He now has the chance to try and change that. Team Corbyn, meanwhile, may well feel it is better to have McBride on the inside pissing out than on the outside pissing in.

In his recent Times piece, McBride also predicted that sacked frontbenchers Michael Dugher and Pat McFadden would seek to oust Corbyn this year. "When the coup comes," he wrote. "It will not be the hapless Hoon and Hewitt waving a letter of protest. It will be Dugher and McFadden in a pair of tanks, with a 200-strong army of MPs behind them. Get ready for your October Revolution, Mr Corbyn." Somewhat ominously for the Labour leader, October is when McBride's contract is due to end.

Labour MP John Woodcock, who worked alongside him at No.10 and represents Barrow, where the Trident successor submarine are due to be built, tweeted: "The reasons he left aside, @DPMcBride has a common touch like few others. Welcome back. No more of your bollocks on Trident though please..." Another Labour source quipped, in reference to McBride's home borough, "The Islington set just keeps getting bigger".