Northern Rhodesia 1938 KGVI ½d Extraneous Ink Streak

1938 KGVI ½d green (SG 25). Block of 42 VF/M/UM showing EXTRANEOUS INK STREAK DIAGONALLY. Eight stamps are affected, strongly over top two rows and trailing off to bottom. Positions 68, 69, 78, 79, 88, 97, 106 & 116. Few printing errors ocurred during production of this issue by Waterlow. Most unusual, interesting, VF.