South Africa 1937 Clouston & Kirby Green London - Cape, Signed

SA: 1937 CLOUSTON & KIRBY GREEN RECORD FLIGHT LONDON - CAPE TOWN: Cover franked GB KGVI 1½d tied by London machine cds 13 NOV 1937 with Cape Town arrival cds 16 NOV 37 struck clearly alongside. Also large rubber "Cape Town Municipal Air-Port Wingfield 16 NOV 1937" cds. Cover bears BOTH THE PILOTS' SIGNATURES - rare thus. Small buff "London-Cape Town Record flight" etiquette. VF, a rare autographed cover as few signed were carried.