Description:

1921 (Dec 4) Perth-Derby #56a Jas A Dimmett Motor Accessories Castrol Oil advertising cover addressed to Derby flown by Western Australian Airways on inaugural flight of Australia's first regular airmail service franked with Kangaroo 3d olive (surface fault) and KGV 2d orange tied Perth cancels paying domestic letter rate plus 3d airmail surcharge with black 'PERTH DERBY/4DE21/AERIAL MAIL' skeleton cachet alongside on face, 'DERBY/20DEC21/WESTN AUSTRALIA' arrival on back, Cat $1,100. [the service was suspended soon after leaving Geraldton on 5 Dec due to the fatal crash of one of the three aircraft; the mail was flown back to Perth and sent on by the steamer SS Bambra]