3d. on Manus (sans serif) (No. 387), fresh color and mostly good perforation, with clear double surcharge, showing the complete surcharge "G.R.I. 3d", unused. Only 5 examples of this stamp with double overprint are known, this is the only stamp which shows the overprint completely double, one of the great rarities, signed Kilian BPP (slightly showing through) and certificate Holcombe (1988)
Reference: depicted in G.R.I. by Robert M. Gibbs, page 98
