FCP = Fluorescent coated paper PVAD = Polyvinyl alcohol acetate dextrin gum
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nd24

ND24 - Northern Ireland 9p bluish violet, FCP/PVAD, two 4.75mm screen 150 phosphor bands (Cyl 1) (Harrison/photo) - Deegam N90.1.1 - S.G specialised XN35 - Stoneham U35 - Concise NI26

Two 4.75mm phosphor bands from cylinder 1 [18.1.78]
phosphor_omitted

ND24mp - Northern Ireland 9p bluish violet, FCP/PVAD, phosphor omitted (Cyl 1) (Harrison/photo) - Deegam N90.1.1a - S.G specialised XN35a - Stoneham U35a - Concise NI26Ey

Phosphor omitted from sheets cylinder 1