Great Britain: 1921-22 Shackleton-Rowett Expedition: GB 1912-24 KGV 1½d brown blk of 4, with 2 strikes of 'TRISTAN DA CUNHA' cachet & central 'SR ANTARCTIC EXPEDITION 1921' cds. VFU, some perfs rejoined. Very rare as only 284 of this value used by the expedition. Certificate can be obtained on request. (P)