BOTSWANA 1976-77 RARE GUTTER BLOCK 7t on 7c Agate, Gemstones issue, with surcharge at bottom right, SG 372a, a spectacular never hinged mint right marginal GUTTER BLOCK OF TEN with “11111” and traffic light colour control symbols in the gutter. A very striking control block of a scarce issue. (block of 10 stamps)