Great Britain. Royal National Rose Society Centenary. Issued 30 June 1970. During repairs to the 13p cylinder, the face value of one of the stamps was covered. The covering was inadvertently left in place during printing, but the error was discovered before distribution and all examples supposedly destroyed. However, a used example (on cover with a Dover cancel dated 23 July) and two mint examples surfaced. Both mint copies are from the same position on different sheets: column nine, row one. Just one mint example, in pair with a normal, remains in private hands. The others are in the Royal Philatelic Collection.
New Hebrides. Constitutional Changes. Issued 29 June 1976. The original printing had to be scrapped due to objections to the inscription on the f1 and f2 values.
India. Michelangelo di Lodovico Buonarroti Simoni’s Birth Anniversary. Issued 28 June 1975.
Canada. Opening of St Lawrence Seaway. Issued 26 June 1959. It’s believed at least 21 uncut sheets of 200 stamps were printed with the centre inverted in error. According to official documents, the bulk were discovered and destroyed. However, five panes of 50 stamps are thought to have reached the market.
Pitcairn Islands. Flowers. Issued 25 June 1973.
Gambia. Founding of Bathurst Anniversary. Issued 24 June 1966. The 1s 6d exists missing silver (the central die-stamped city arms). The error is only recorded used off-piece with part circular Bathurst cancel.
Nigeria. Driving on the Right. Issued 23 June 1972.
Bermuda. Anniversary of US-Bermuda Yacht Race. Issued 22 June 1956.
Zanzibar. Definitives. Issued 21 June 1964.
Great Britain. Modern Architecture. Issued 20 June 2006.