Chancellor announces ‘widest set of reforms’ to investment and banking in Mansion House speech

Rules matter. Regulation and deregulation can both lead to profound change.

On October 27 1986, a radical shift in financial regulation transformed the City of London. The “Big Bang” introduced electronic trading and opened the doors to foreign banks, turning London into a global financial powerhouse.

It made the city roar, boosted the economy, created thousands of high-paying jobs and swelled the Treasury’s coffers. But the direct benefits weren’t felt much beyond London and the South East.

On Tuesday, the chancellor hopes to make some noise of her own.