Led by the US, the entire world is in a debt spiral, and just like many of the systems that sustain modern civilization, the global economy itself is in various stages of unraveling from its unsustainable path [1]
A little to coarse, since OP asked about the UK. But Obama already acknowledged that the US will never pay back all their debt, "even if they get 10% GDP increase per year for every single year" if I am not mistaken about that non-verbatim quote.
Are you potentially not a creditor? I think the term here is 'distinction without a difference'. If you lend the US enough money for a sandwich, you should expect not to get a sandwichworth of money back. What you call that legally is not that interesting, I suspect, to the people were lending the money.
It doesn't matter what happened to creditors centuries ago. As it stands right now it is inconceivable that the US could or will pay off all its present and future creditors in real terms. Someone has lost a lot of money (presumably China and Japan). How could the US pay them back without resorting to fantasy? The debts are too high and the US economy is not big enough for any strategy to be politically feasible. Even coming up with a serious scenario where the US tries to pay down its debts is hard. It is likely that they are going to keep running up debts until they can't pay the interest any more, then default.
The best outcome the US can achieve is semantic games where they pretend that giving people back less than was borrowed is somehow reasonable.
Monetarily sovereign countries like the US, UK, Australia, Japan etc. (but not Euro using countries because they can’t control their own currency) don’t really have to. They can just keep rolling things over for as long as they want. If private markets don’t want to buy bonds (they will tend to though because it’s basically risk free), the central bank can.
It’s not the money that’s the issue - that’s an abstract, invented thing. The limits are inflation, natural resources and available labour.
That quote doesn't surprise me, politicians are stuck between a rock and a hard place without any real options to solve systemic issues. Just like with climate collapse, the solutions that tackle the problems at their core require what is effectively political suicide.
Political suicide sounds far better than the economic and environmental suicide path we've been on for the past few decades in the name of lower costs and more profit.