John Sutherland (Professor Sutherland to you) is a widely respected observer of the literary scene, and he has an enlightening piece in the Telegraph about the changing features of bookselling in the UK over the last hundred years or so. (Link via booktrade.info.)
Once upon a time, bookselling was the occupation of gentlemen scholars, who did not go around trying to cut each others' throats. All that is past. At least according to some. Booksellers may still be gentlemen and scholars (I know a few), but the competition is fierce. Sutherland gives an account of how and why.
What John Sutherland doesn't do -- it's a short article -- is point out that the high street bookshop is no longer the only place to go for your books. And while your local Waterstones or supermarket may have only a limited stock of bestsellers, there is another source of supply which can offer you a couple of million books, some of which struggle to sell more than ten copies, but which meet the needs of a particular type of customer.
No prizes, even though it's Christmas, for guessing where that source of supply is. But here's a clue.