"You also haven't quite thought out where we're going to get 25 trillion quid from."

Dead simple, Steve! Just do what the Federal Reserve does in the USA...create it out of thin air in the form of new debt owed TO the Federal Reserve by the rest of society!

This is what has been done as a standard routine by the Fed (and other major banks) for a long time now, and it's why a movie now costs $9.00 whereas it used to cost 25 cents in my mother's youth. The real value of a night out at the movies hasn't changed one iota in all these years, but the money supply has been inflated almost beyond comprehension, and the money itself has accordingly declined greatly in value, and continues to do so.

One difference though: All that magically created money that arrived "Presto!" in the ecomony when the banks created it by making loans didn't get distributed to the general public in the form of cash. Certainly not! It got distributed to the general public in the form of an ever-increasing national debt which they are expected to pay down through their taxes...and through inflation...while the moneylenders (banks) got rich on the interest charges.

And when the moneylenders' bubble bursts, as happens now and then, and there is a major recession or even possibly a depression to deal with, then they get bailed out with more public money, because they are considered "too big to be allowed to fail". And the debt rises even more. And so do the interest charges.

That's what I call a sweet deal....for bankers. Certainly not for the rest of us.