See Emily Play was released as a single but Bike wasn't, and I got the impression somewhere that back in the mid-60s it was reasonably common in the UK for singles to be released just as singles and not also included on albums.

Certainly The Beatles did this with, for instance, Penny Lane/Strawberry Fields, both recorded for Sgt Pepper but then left off when released early as a double-A side. Wikipedia says "The Beatles usually did not include songs released as singles on their British albums"; though these two were later put on the Magical Mystery Tour LP.

On the other side, the album Days Of Future Passed by The Moody Blues contained their best-selling single Nights In White Satin as an integral part (the album is the story of a day with Nights at the end), so I suppose there's no hard and fast rule.

All those albums are from 1967.