Angela Rayner has been made a full member of the UK’s national security council (NSC), following a U-turn by Sir Keir Starmer.
The deputy prime minister’s name did not appear on a list of ministers attending the committee published by the government last week.
But the document has now been re-published to include her as a member, confirming a move first reported by the Guardian.
The newspaper reported the new No 10 chief of staff, Morgan McSweeney, had pushed for the change in a bid to shore up her position.
Downing Street said she had previously attended NSC meetings, claiming the change merely “formalises” an expectation she would do so regularly.
First established under former prime minister David Cameron, the NSC brings together senior ministers and defence and intelligence chiefs for meetings on security issues. Its members are appointed by the prime minister.
It membership has fluctuated over the years and varies by issue discussed, but has typically included previous deputy prime ministers as standing members.
The only exception was Therese Coffey, who held the post during the 49-day premiership of Liz Truss.
Ms Truss who effectively put an end to the NSC by merging its functions with two other foreign policy committees, before it was later reinstated by Rishi Sunak.
Topics discussed at the NSC include foreign policy, defence, economic security, and resilience to security threats.
Its membership was slimmed down in July 2021under Boris Johnson, in a bid to keep discussions “focused and strategic”.
Alongside Ms Rayner, the committee will be attended by Chancellor Rachel Reeves, Cabinet Office minister Pat McFadden, Home Secretary Yvette Cooper, Foreign Secretary David Lammy, Defence Secretary John Healey and Attorney General Lord Hermer, and will be chaired by Sir Keir.
Mr Rayner, who is also the housing secretary, also holds seats on cabinet sub-committees discussing constitutional matters, home and economic affairs, and changes to employment law.
