Well into the 1980s, unfortunately, and often coupled with shoddy "perfect binding" that ensured the complete disintegration of books if you actually read them. Even now, you don't get acid-free paper automatically; I think it costs more, but it's worth it.

The chap in the middle is one of the singers featured in the book. He's in Sunday Best for a portrait at the local photographers, though; his working clothes were a bit different.