Well, I can’t blame the bookseller for his business acumen. Certainly he had no particular business incentive to be nice, if they were going to sell off every old book they had and never buy any more until he was dead and gone; and if he was going to be able to retire wealthy off the profits.
But geez, this is sharp practice. And geez, the people who run Truro Cathedral must never had heard of selling books piecemeal. Even on E-Bay.
Umberto Eco wrote a novel about this, but I guess the Truro folks aren’t big on Eco.
I believe that this sort of thing used to be known in the book trade as ‘book stealing’ at one time.