TTT seems to be way out in assuming who we owe money to.
Countries borrow money through issuing bonds. Anyone can buy them but, in practice, the vast majority are held by countries with booming economies. For example, if China decided to call in all of the debt that it holds in the form of US bonds, it could wipe out the US economy in an instant. (China would never do so though, simply because a collapse of the US economy would seriously harm its own economy).
Similarly it's China that holds most British bonds. In purely financial terms, both the USA and the UK are almost wholly 'owned' by China (which might, just possibly, explain why both British and US politicians are often keen not to upset the Chinese government)