The first question I tried to answer was which of the four covers that I know of was authorised by The Salvation Army. Figure 1 shows a proof of the cover that was initially authorised. However upon submission to Buckingham Palace for approval, the S.A. were informed that they could not use a picture of Princess Diana on the cover. A second authorised cover was hastily produced, and further inquiries revealed that this was the only cover that was authorised by The Salvation Army for production. As a second cachet had to be produced the covers were not available for sale at the Carols at Christmas event in any great number. Consequently a considerable number remained unsold, and these were purchased by a Salvation Army officer who I believe still has them.
The next question then was why were the three covers with portraits of Princess Diana produced given that they were not authorised by The Salvation Army? Interestingly all the covers bear the same Benham's reference number, SA3. The pictorial postmark is undoubtedly authentic, and the covers are certainly all Benham's 'Silks'. This proved difficult, as Benham's were unable to provide any information. As I am certain that the covers with portraits of Princess Diana on the cachet were unauthorised, who produced the covers and why? One can only speculate as to the answer. Was it some over zealous employee trying to create a rarity by producing very small quantities? Or was someone trying to be economical by using up surplus covers from previous issues? But if this were the case why do all the covers bear the same reference number? As I said earlier, answer one question and uncover more that don't have answers.
The contract between The Salvation Army and Benham's was for a specified quantity of covers which were duly supplied. Buckingham Palace refused permission for the use of any cachet depicting Princess Diana. The Salvation Army apparently received an assurance from Benham's that the pictorial postmark would not be used on any other cover. Until quite recently one of the Salvation. Army officers responsible for commissioning the cover was unaware of the existence of any other cachet apart from the authorised one.
So there you have it. Much about this issue remains a mystery, but at least 1 now know which was the officially authorized cachet! Unfortunately why the other covers were produced and by who, still remains a mystery. Maybe other members can add to this information, it would be great to have all the answers instead of just some.