Swingin' Pig's 'Ultra Rare Tracks' was one of the first collections to appear in the late 80s that featured mainly unheard studio outtakes in very high sound quality. Yellow Dog's Unsurpassed Masters series and the Backtrack series followed shortly thereafter. While the Ultra Rare Tracks discs sound quite good, they are all fairly short and none of the discs are presented in chronological order. In addition, many of the liner notes contain inaccurate information.

Of all the early sets, I prefer the Backtrack series, which features many takes of the songs back to back and not spread over several discs. All of this material has been released many times on other boots and much of it appeared on the Anthologies. Volume Four is notable for the inclusion of a Blues Jam and a version of 'Yer Blues' from the Rock and Roll Circus. For the rest of this material, you're better off getting it all on the Artifacts box sets, along with a wealth of other rarities not included on these discs.

Volume Four
1. One After 909, Twickenham version, 1/69
2. A Taste Of Honey, take 7
3. I Feel Fine, take 7
4. Yer Blues, from the Rock and Roll Circus film
5. Blues Jam, from the Rock and Roll Circus film
6. Not Guilty, EMI fall 1968
7. Get Back, Twickenham version, 1/69
8. Mailman, Bring Me No More Blues, Get Back sessions, 1/69
9. Do You Want To Know A Secret, take 4
10. All You Need Is Love, sourced from 'Our World' television special