KUT 1949 KGVI 40c Imperf Printers Trial Block

1949-52 KGVI 40c Crowned Cranes IMPERF PLATE PROOF / PRINTER'S TRIAL: Block of four on greenish buff paper with additional overrun of other values, at least TRIPLY so. Vignettes of Lake Naivasha mirror images on reverse. Interesting piece presumably from the printer's working proofs, an unusual combination for these.