Gibraltar 1938 KGVI 3d Imperf Printers Trial Block

1938 KGVI 3d Europa Point overrun with KUT 10c Lake Naivasha IMPERF PLATE PROOF / PRINTER'S TRIAL: IMPRINT PLATE NO strip of four on greenish buff paper with additional overrun of the KUT stamps. Further KUT values on reverse. Interesting piece presumably from the printer's working proofs, an unusual combination for these, the first such encountered by us.