KUT 1949 KGVI 10c Imperf Printers Trial Block

1949-52 KGVI 10c Lake Naivasha IMPERF PLATE PROOF / PRINTER'S TRIAL: Block of four on greenish buff paper with additional overrun of the alternate colour: ie the block shows the 10c brown & grey and 10c black & green. Frames inverted to vignettes, imprints in both colours. Interesting piece presumably from the printer's working proofs, an unusual combination for these, the first such encountered by us.