When accountants at mid-tier firm Moore Kingston Smith began using artificial intelligence to speed up their work, profit margins jumped.

Colleagues in another team running checks against corporate fraud created a report for customers in two hours, something that previously took two weeks.

The rollout of AI is raising hopes that Britain¡¯s economy can escape the productivity problem that has dogged it for two decades, even as slow growth pushes finance minister Rachel Reeves toward tax hikes in Wednesday¡¯s budget.