I always thought that this series ended at #54 but Keith Lowndes very kindly sent me the cover of a #55 dated 20th Oct 1973.
#40 1st amalgamation with Once Upon a Time.
Red binders were also available with a gold embossed Walt Disney's Now I now and a Mickey Mouse illustration. These binders comfortably hold 25/30 issues. To get all 55 in one bider is a bit of a squeeze!
Note: some PR issues may have no value. Selected issues in FN, VF or VF/NM may not exist in some titles.