Union of South Africa 1930/45 Roto 1/2d top left cnr B4 without flaw at Pos. 1/1

1930/45 Pretoria roto definitive issue, ½d grey black and green top left corner block of four duties without flaw at Pos. 1/1 - thus from the June 1934 printing (Issue 3). Scarce proving piece. Hinged in margin, stamps superb unmounted. SG 42. UHB 36.