Dubious move on the part of Proper. If you're putting together a box of Hayes from that period, surely you know that his fans want that album and they want ALL of it.
I for one was going to order the box but now will not.
It could be a licensing issue. The tracks included on the Proper set are those that were originally issued on the Fontana/Epic album "Tubbs in New York". The "missing" tracks are those that subsequently appeared on the CBS CD "The New York Sessions". I seem to recall some discussion previously (here?) about the CD having to be withdrawn because CBS did not have the rights to re-issue it.
Proper doesn't seem to concern themselves with things like "licensing rights.";)