The transitional period between the change of name from North Borneo to Sabah just before becoming part of Malaysia was and is confusing philatetically for both the postal authorities and collectors. The old cancellers were used before the arrival of the new ones. The 1961 adhesives were eligible for use until and also after the overprinted with "SABAH" stamps became available on 1st July 1963.
Sabah only became part of Malaysia on the 16th September 1963 after adopting its present name about 2 week s earlier on 31 August. Sabah was actually the old name that was used when it was part of Brunei. The very old official documents would have this name until it was changed by the British.
The origin of this name remains obscure but I favour the theory that it was derived from an old Bruneian Malay word meaning "north of the river" being situated to the north of Brunei.
The above FDC has the colonial Australian type cancellation of Sandakan North Borneo dated 16SE1963 on the first issue of Malaysia stamps. The label on the top left corner was pasted to hide the wrong date of 31 August 1963.
This is a commercially used item with the Australian type cancellation of Tawau Malaysia with a date of 9OC63. These 3 covers were obtained last weekend in the auction during the Sarawak Specialist Society AGM weekend. Many exceptional items were shown and discussed over those 3 days. The auction had a wide and in depth range of material which is not normally available elsewhere. To take part, one has to be a member. The annual subscription is £15 including 4 journals where you may see some of my contributions. A link to the society website is to be found towards the bottom of this page.
Similarly, we have the not overprinted North Borneo stamps used after the name was changed to Sabah with the corresponding cds. The last set of North Borneo stamps which originally came out in 1961 was valid until the end of 1971. So potentially there are quite a few of these covers and single stamps like the ones I showed previously by clicking on the link here. But in practice that is not so. Perhaps there are more of these items locally in Malaysia or Singapore.
The challenge is to collect the more obscure post offices of that period and this includes the North Borneo cancellations on Sabah/Malaysia stamps and covers. Strange enough I can not find the date as to when these Sabah Malaysia cancellations started.
Actually, the very collectible are the various town triple ring cachets used to endorse covers of this period. Unfortunately, I do not have any to show. They are expensive but I do know of people who have many.
The other points of particular interest in this cover would include that this was a leftover colonial official cover which should have had the OHMS bit crossed out. Strangely enough, it has a post date of 14JUL64 and the blue endorsed cachet has a date 13 JUL 1964 from some department in Tanjong Aru Jesselton. The top right of the stamp also has the perforation guide line.