Sri Lanka 1978 25c Troides Helena –imperf discovery

A traffic light/plate 1B–1B–1B–1B block of the 25c Troides Helena value from the Sri Lanka butterflies commemorative set issued 28 November 1978 has surfaced imperforate to top margin. The variety emanates from the original Waddington printing rather than 5 January 1990 Questa printing. Previously unrecorded, just ten stamps from the top row of a pane would have been affected.

See here for a similar variety on the 50c value.