Lot 60031 – 1980-81 Aircraft imperf. plate proofs on Harrison

1980-81 Aircraft imperf. plate proofs on Harrison and Sons presentation cards, the 1c with central design of the issued 2c, 2c with the central design of the issued 3c and the 3c with the central design of the issued 4c, minor toning to the 3c and proof and odd spot on the cards, unique trio, ex Bradford, plus two commercial cover usages