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.