Budgets are all about numbers: growth, inflation, unemployment, headroom. So this week on Westminster Insider, Sascha and Pat look into the numbers behind Britain’s economy — and just how much government policy is really made up of guesswork, rather than solid measurements.

Sascha talks to Dr Laura Gilbert, the former director of data at Number 10 Downing Street, who explains exactly why the numbers we have on measurements like immigration or the workforce are often wrong by hundreds of thousands of people.

Ben Warner, who was chief advisor on data and digital at Number 10 during the pandemic, explains why this uncertainty spells chaos for political decision-making and says he believes most ministers don’t know how to use data.

Andy Burnham has promised Britain can “hope again”. But with inflation rising, borrowing costs soaring and trillions of pounds of national debt, how much room does Chancellor John Healey actually have to deliver in the budget on Oct. 28?

This week, Pat and Sascha speak to Treasury insiders to find out who really calls the shots when a Chancellor puts together a budget. First, they hear from Matt Pound, one of former Chancellor Rachel Reeves’ closest advisers, about the tough choices facing Healey, the dangers of leaks and U-turns, and why keeping the bond markets onside matters more than politicians might like to admit.

Then, Cameron Brown, who worked under both Kwasi Kwarteng and Jeremy Hunt, and Simon Finkelstein, who advised Hunt at the Treasury, reveal just how obsessed Westminster has become with the bond markets. And POLITICO’s Financial Services Editor Fiona Maxwell gives her predictions for what Healey might have in store on budget day.

CORRECTION: This podcast has been updated to correct the description of Simon Finkelstein’s role.