I bought this short BMA set at our recent society auction. It is clearly philatelic with a combination of corresponding values from North Borneo and Sarawak. The British Military Administration looked after Brunei, Labuan, North Borneo and Sarawak as a single region. The BMA overprinted stamps were eligible for use throughout the area. No Brunei were overprinted in this way. It was said that there were no spare sheets of mint stamps left after the war which I do not think was true.
You can see the setting is the reverse of that for Sandakan. There are 3 main subtypes of this linotype. This is type 1 and is quite common whereas types 2 and 3 are difficult to find. Type 2 has smaller numerals and has a slightly different setting. Type 3 does not have the year and both day and month are in numerals.
We have a clear common date of 17/DEC. 1945 and in fact this is the date on cancelled for favour sets and covers. The above is rather unusual and attractive with combinations of NB and Sarawak adhesives on piece.