RE Series No 38
Date: 22 December 1977.
Title: 35th Anniversary Invention of the Flail Tank.
Type: Commemorative Cover.
Stamps: 8½ᵖ "Silver Jubilee" commemorative, issued 11 May 1977.
Special Handstamp: Corps of RE, 35th Anniversary Invention of the Flail Tank (scorpion), BFPS 1572, Silhouette of the Flail Tank in the centre.
See: Wiki - https://en.wikipedia.org/wiki/Mine_flail