Last week, Centre for Cities co-organised the first international metro mayors' summit, bringing together England's new metro mayors with counterparts from cities across the US. During the discussions it was striking how much the UK and US leaders have in common – from the values they espouse to the challenges they share, such as supporting local businesses and economic growth.

However, one big difference stood out: the disparities between the UK and US mayors in terms of the powers they wield, particularly over fiscal matters. According to the OECD, local government in the US controls nearly 50% of total national expenditure, compared to just 25% in the UK.