The former prime minister, who was forced out of No10 in 2022, is the only party leader under whom the Tories poll higher than their opponents on the right.
Pay review bodies have recommended 4 per cent for teachers and 3 per cent for NHS workers - significantly more than the 2.8 per cent the government has proposed.
Amid mounting fury at the Labour-run council over the chaos, with rubbish piling up and rats running riot on the city's streets, No10 urged Unite to negotiate 'in good faith'.