Cook Islands
1973 QEII’s Coronation 20th Anniversary, IMPERFORATE M/S
On white gummed paper, Mint Not Hinged
Stanley Gibbons Catalogue: #MS430, Value £2.50 (2013) for a Miniature Sheet
Plate Proofs or Imperforate are not listed
Scott Catalogue: #350 Value US$3.50 (2009) for a normal Miniature Sheet
Plate Proofs or Imperforate are not listed
I believe this to be a Plate Proof. The printer of this stamp issue Fournier S.A sold its philatelic archives of stamp artwork and proofs in 2007 through the German stamp dealer and auction house Gärtner.