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My brother in law is making real interest payments on collateral in his property that no longer exists. If it no longer exists (the £25k negative equity) how about the banks wiping it off his outstanding mortgage ?
Your brother-in-law made some disastrously bad financial choices, apparently. As did the banksters.
Oddly enough, if banks collapse, they take down your country's economy with them. Your brother-in-law"? Not so much.
Tell your brother-in-law to consider personal bankruptcy, that's sorta like bailout for small-time losers.