Great Britain Australia 1934 Rosecoe Turner Signed Mac Robertson Air Race Airmail Cover

Cover franked with 1/2d KGV of Great Britain, tied by London machine cancel (11 Oct), and 1d KGV of Australia, tied by Melbourne c.d.s. (23 OC), violet Mac Robertson Air Race flight cachet signed "Roscoe Turner" below, no backstamps, scarce and fine; Roscoe Turner was a 3-time Thompson Trophy Air Race winner.