In his book Sapiens, Yuval Noah Harari makes the case for why some European powers failed to prosper while others prospered.
He writes that Spain failed because the Crown was autocratic and simply cancelled its obligations to pay its debts.
Britain, on the other hand, prospered because its overseas ventures were led by merchants who paid their debts.
Britain earned a reputation as a safe place to lend, and so its interest rates remained low.
Through the centuries and up to and through all the troubles of the 2008 crash and its aftermath, Britain has been able to borrow at very low rates.
All that could fall apart in a heartbeat if Britain walks out of the EU without resolving its obligations.
Think on that, ye merry Brexiters.