Great Britain 1840 1d Black Plate 4, SG2Great Britain 1840 1d Black Plate 4, SG2. A very fine used close to large four margin example lettered OB, neatly cancelled by the distinctive violet Maltese Cross. Violet cancellations were from Market Street, Hertfordshire, Glasgow and Manchester only. A magnificent exhibition quality example of this lovely coloured cancellation, very rarely seen in so fine a condition. Accompanied with a 1996 British Philatelic Association certificate of