So it looks like, historically at least we aren't particularly high (or low) in debt relative to gdp? Pretty much in some average historical range?

Those forecasts look scary though, wonder how they came to that conclusion?

What debt ratio is meant to be sustainable anyway? Wouldn't it change depending on how much a country owns in terms of assets (including overseas assets when Britain was an imperialist -prior to 1914)?

EDIT: come to think of it, does the GDP include overseas territories under British imperial power? If so that might explain the fall in the 19th century queen Victoria rule.

Maybe 100% debt to gdp and beyond is actually sustainable?