Would like to update on this topic. The stamps imaged were not produced by the Format International Security Printers. They were produced by The House of Questa.
The House of Questa produced the majority of the 1981 Royal Wedding Omnibus series under direction of the British Crown Agents. The Format Printers only produced for the imaged series for the country of Sierra Leone which I might add had no errors.
In my studies on the printers it is now a proven fact that the House of Questa did indeed print varieties and errors on a massive scale. They surpassed what the Format Printers produced by a long shot! You can now basically say that all printers and the majority of agencies have and are to this day producing made for collector varieties and errors for the majority of countries.
The only reason the Format Printers continually get brought up in regards to producing these varieties and errors is because of the trials which exposed the documents showing what they were ordered to produce by the agencies. It is standard practice for security printers and the agencies they work under to destroy all documents after a given amount of time...usually when the stamp issue is demonitized. Try to find them and you will see that 99% of all documentation on the printers side no longer exists.
You can view the evidence on this issue and just how massively The House of Questa produced errors and varieties for this issue on my website. Here is the link.
*** Edited by Staff - Please Review the rules that you agreed to when you registered. ***Valuation of stamp varieties and errors from the early 50's to today needs to be determined on rarity based on what was produced purposely rather than thinking of them in terms of discovery. It is a great possibility that even the famous U.S. Inverted Jenny stamp error was indeed...purposely made.