What is the UK’s public debt?

“In 2010, when the Conservatives took over, national debt was £0.95trillion. So they promised to reduce it and said we can trust them with the economy. But now it’s £2.0trillion.”

Facebook post, 30 March 2019

These figures are not accurate, but they are in the right ballpark.

In its first budget in June 2010, the Coalition government, led by the Conservatives, set a target for debt to be falling as a percentage of the size of the economy (GDP) by 2015/16. That target was missed, and debt on this measure has only started to fall in the last year.

In May 2010, when the Coalition began, the national debt (excluding debt held by public sector banks) was £1.03 trillion. As of March 2019 it had risen to £1.80 trillion.

You can also measure debt to include the debt held by public sector banks (those banks that were partially or wholly nationalised during the financial crisis). This measure isn’t as commonly used, however, as it can distort the underlying figures.

On this measure, debt has fallen from £2.3 trillion in May 2010 to £2.1 trillion in March 2019, because the debt attributable to those banks declined sharply as many of the government’s holdings in them were sold back onto the open market.

So the claim has close to the correct figure for May 2010 using debt excluding public sector banks, and close to the correct figure for the present day using debt including public sector banks. But they’re obviously not comparable. 

 Regardless, debt as a percentage of GDP is a better measure for making comparisons over time. Looked at this way, debt (excluding public sector banks) rose from 65% of GDP in May 2010 to a peak of 86% in September 2017, before falling back to 83% as of March 2019.