The authority is to refer the decision to move Principal Treatment Centre care directly to the new Labour Secretary of State for Health.
It’s the next step of a coordinated cross-party campaign from Richmond, Merton, Kingston, Greenwich, Surrey and Sutton.
Cancer services for children aged 15 and under are currently provided by the Royal Marsden in Sutton and St George’s in Tooting.
But following a consultation, they will be provided at the Evelina at Waterloo post October 2026 in a move backed by NHS England.
A petition calling to stop the move reached almost 12,000 signatures at the time of the decision in March.
It was backed by parents, campaigners, MPs and the leader of the Lib Dems, Sir Ed Davey.