Great Britain 1966 4d British birds (Ordinary) error, SG696ag.
A superb unmounted mint left hand marginal block of four, with full original gum.
The error with bright blue omitted affecting Black headed Gull (water) & Blue Tit. Offered with normal block for comparison and presentation.
A scarce Queen Elizabeth II stamp error of missing colour. Pierron records only 40 mint blocks in existence.
