This is the description of what happens in Madrid with its Bibliometro scheme:
“Bibliometro libraries can be found in a handful of the busiest Madrid metro tube stations. A membership scheme gives readers access to a selection of literature recommended by librarians. Books can be returned via drop-boxes, convenient for the rushed commuter, or exchanged for another book.”Add to that the book vending machines they have in Paris and you start to get a theme here about books being made more widely available and that would be a great thing not just for London but for many cities.