Copies of the leaflet, containing pictures of the five 26p stamps (pictured), were then hastily withdrawn and destroyed by the Post Office, but at least one survived.
Peter Jennings, a collector, said he understood Buckingham Palace had given initial consent but Earl Spencer, Diana's brother, had intervened to delay the commemorative issue.
"I appeal to Earl Spencer and his family to allow Royal Mail to issue the Princess Diana stamps in the near future," he said.
"Postage stamps would make a wonderful and lasting tribute to the Princess, and would be collected by philatelists and non-stamp-collectors throughout the world for years to come." The idea for the stamps was put "on hold" last week after a Palace spokesman said the Spencer family wished to delay the issue to allow further consideration.Reuse content