This is a note about the bookshop, not about the song by Bob Dylan, but there's probably a connection between the two if you ask the staff where the name comes from. No disrespect meant to Balham, but this probably isn't the sort of place you'd expect to find one of London's best book shops but yet here we are, cool name and all.
Why does this qualify as one of the best bookshops in London, then? Surely it's not just the name? It's the range. They have new and second hand books all in together like you don't mind if you buy a new or used book, which in many cases you don't really, do you? Their attitude is that lots of great books are out of print, so if you want to read them you best get a second hand copy then, while you still can.
Genres of all kinds can be uncovered here, from modern poetry that doesn't rhyme, to classics, to books that will be classics in the future but aren't yet, to random German philosophy and historical novels about events you've never heard of.
My Back Pages also have a very good shelf system, complete with informative signage, so it's pretty easy to find what you want despite the stacked shelves and additional stacks on the ground. Not all bookshops do and sometimes it makes for optimum browsing if they don't but there's something particularly pleasurable about being able to uncover the book you're looking for yourself without having to recourse to an extended conversation about your literary choices with a member of staff. The staff here have a reputation for being helpful, but sometimes you don't want a literary-cool-kid to judge you for not having read Heart of Darkness yet, despite the fact that you've written more than one essay that has referenced it.
Prices are reasonable for what you're getting this might be one of the main advantages of Balham. There are some modern first editions that you could still pay less than they're really valued at for, new books you'll pay cover price for and a bin out the front with books for 50p and some of these are very good books as well, not just piles of D*n B***n.
What you do need to be able to afford when you come here is time. It's easy to loose a coupe of hours amongst the tightly packed shelves.