If he has some real estate or other properties he just selling them to the bank for Ł200k.
Not a bad deal because once dead he will not need these properties and the bank will just auction them to cover the costs of the loan + some extra cash.
I guess he must have some house or some land on his name appraised at near Ł250k or a bit more, so the bank will have absolutely no problem recovering the money from the loan.
If I was 102 years old I would do the same
also think about how much free advertisement is that for the bank. Basically for $400k you appear on every news media on he world