GB 1973 Explorers 3p Se-tenant Pair Gold & Phosphor Omitted Unmounted Mint

Great Britain 1973 Explorers 3p + 3p se-tenant pair featuring David Livingstone and Henry Stanley, unmounted mint, with gold Queen’s heads and phosphor omitted. A normal unmounted mint 3p se-tenant pair is included for comparison. The vendor’s estimate is that approximately 60–100 pairs with the combined omissions exist, whereby Gibbons does not list these combined varieties. References supplied: SG 923b variety / 924b variety.