Graphite line

Graphite lines were printed on the backs of Great Britain Wilding definitives beginning in December 1957.

One or two vertical lines were printed on the most commonly used values, the 2d with one line, the other low values to 3d with two widely spaced lines each. This allowed detection and sorting by new postal machinery.

In November 1959, graphite lines were replaced with phophor bands on the faces of stamps. 



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