p1
Paper varieties viewed under long wave light.
BCP = Bluish coated paper PVA = Polyvinyl alcohol acetate gum
OCP = Original coated paper
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P1 - 1/2d Orange brown, BCP/PVA, two 4.75mm screen 150 phosphor bands, head A1, upright print (Cyl 2) - Deegam PD 1.1.1 - S.G specialised U1 - Stoneham M13 - Concise 723

Bluish coated paper, screen 150 phosphor bands from cylinder 2 [5.2.68]

P1mp - 1/2d Orange brown, BCP/PVA, phosphor omitted (Cyl 2) - Deegam PD 1.1.1a - S.G specialised U1a - Stoneham M13a - Concise 723Ey

Bluish coated paper, phosphor omitted from cylinder 2

P2 - 1/2d Pale orange brown, OCP/PVA, two 4.75mm screen 150 phosphor bands (Cyl 3)

Original coated paper, screen 150 phosphor bands from cylinder 3 [3.69]