FCP = Fluorescent coated paper PVAD = Polyvinyl alcohol acetate dextrin gum
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sd23

SD23 - Scotland 5.5p deep violet, FCP/PVAD, two 4.75mm B3 phosphor bands (Cyl 1) (Harrison/photo) - Deegam S55.1.1 - S.G specialised XS43 - Stoneham S42 - Concise S21

Two 4.75mm B3 phosphor bands from cylinder 1 [23.1.74]
sd24a_24k

Centre band

SD24a - Scotland 5.5p deep violet, FCP/PVAD, 4mm B3 phosphor, centre band, APS perforation (Cyl 1) (Harrison/photo) - Deegam S55.2.1 - S.G specialised XS44 - Stoneham S43 - Concise S22

APS perforation from cylinder 1 [21.5.75]

SD24k - Scotland 5.5p deep violet, FCP/PVAD, 4mm B3 phosphor, centre band, KAMPF perforation (Cyl 1) (Harrison/photo) - Deegam S55.2.1a

KAMPF perforation from cylinder 1 [1976]