These were still in use in 1953-54. It is not known how may of these are still in use in the U.K. today.

Size Abbreviation   Measure (Inches)   Foolscap octavo F8   6¾ x 4¼     Crown octavo C8   7½ x 5         Large crown octavo lC8*      8 x 5¼   Demy octavo D8   8¾ x 55/8     Medium octavo M8   9½ x 6         Royal octavo R8     10 x 6¼   Imperial octavo Imp8  11¾ x 7½     Foolscap quarto F4    8½ x 6¾     Crown quarto C4     10 x 7½    Demy quarto D4  11¼ x 8¾      Medium quarto M4    12 x 9½   Royal quarto R4 12½ x 10        Imperial quarto Imp4   15 x 11     Foolscap folio Ffol  13½ x 8½      Crown folio Cfol   15 x 10     Royal folio Rfol      20 x 12½   Imperial folio Impfol      22 x 15½

^* l = large, s = small may precede some abbreviations.