8p Red Missing Phosphor

1979 SG X879y 8p red Missing phosphor. a few sheets of cylinder 14, thick course paper, had phosphor weak printings mostly on the right edges, though sometimes on left. these result in various degrees of phosphor omitted, with a few, about 4 per sheet, fully missing phosphor. arount 25 sheets turned up around Croydon and Beckenham. Presumably a top up printing as cyl 14 is fairly difficult and its partner cyl 13 almost impossible. cat £475