I finally purchased this double CD after owning a vinyl copy for over 30 years, just to see what versions of the tracks I would get.
I was delighted, therefore, to find that: -
1) With one exception (The Young Ones), those tracks only ever mixed in mono (Living Doll, Move It etc.) are also presented here in proper mono, and not mono reprocessed to stereo. This is a big plus over the vinyl version which gave us the mono mixes overlaid with stereo effects that made Cliff and The Shads sound like they'd recorded their tracks in a shower booth. (Even some of the true early 60s stereo tracks on the vinyl version seemed to suffer from the "shower booth" effect.)
2) Some of the early tracks found on the vinyl release in mono reprocessed to stereo (Theme For A Dream, Do You Want To Dance, etc.) are now available in true stereo, i.e. they've used the genuine stereo masters for this release.
3) The real biggie for me is that this is the only Cliff CD compilation that I've found that uses the right take of "Bachelor Boy." It's presented here in discrete stereo, suggesting that it was mixed down onto two tracks prior to producing the mono mix. The vinyl version of 40 Golden Greats, the Singles Collection CD box set and The Whole Story double-CD all use a different take wherein Cliff gives us a meant-to-be-rousing "Yeeeeaaah" before he launches into the final chorus. This "Yeeeeaaah" wasn't there on the original single. The only other non-vinyl-single release that I have with the correct version on is a stereo vinyl re-issue of the "Summer Holiday" soundtrack LP.
On the downside, some of the masters used are a bit rough in quality, lacking in both the bass and the treble departments. I'll forgive this, however, because the upsides make the purchase so worthwhile and get right a load of things that even "The Singles Collection" gets so wrong.