A very fine used single of the 1d on 2d chrome yellow from the 1893 Surcharged Issue, crown cc wmk, crisp GPO grid cancel.
Normally this issue is on the perf 12.5 stamp with upright wmk. The cancellation lies on top of the green ink, so it would seem that the printer ran a sheet of 2d stamps through the overprinting process to test the plates prior to changing the font of '0' and the 'P' to smaller letters.
Gibbons doesn't list this variety, so we estimate it at $500. The stamp offered here grades 80 as follows:
