The real question is "what about locking up a guy in jail for one night costs 20 grand?" That sounds like a fishy statistic to me.

If you divide how much it costs to have a prison by the number of inmate-nights served in it, you MAY get a figure like 20,000 quid per inmate-night (but I doubt it).

Even if it DOES come to this figure, though, it's not true that locking up the banana guy cost that much. His absence would not have allowed them to close the prison, so the taxpayers would have paid just as much; it would have been divided among fewer prisoners that night, is all.

AND a dangerous banana-wielding scofflaw would have been on the streets. Just think, he could have killed several silent-movie actors with the peel alone!