A most attractive Lim Keng Fatt cover with Jesselton R3

Something to lift the gloom that usually follows the recent winter festivities. I was initially hesitant to acquire this cover due to the suspicious looking double ring Jesselton postmark. But the rest of the cover seemed authentic enough and the price was very reasonable. I realised its value following the advice of a friend who is a fountain of knowledge in matters NB.
Firstly, we have 20c in 1909 stamps arranged in an attractive fashion franked by Jesselton D3 postmarks. This handstamp was in use between 1907 and 1914. Somehow it was used late in 21 NOV 1919 on this envelope. By this time, the handstamp has become worn and distorted with the letters of the town indiscernible. As a result, the postal clerk had to apply it with force and that created the double ring effect.
There are transit markings for Singapore 10am 28 NO 1919 and London 3 JA 1920. The latter is a registered mark in red.
The most eye catching is the red cachet at the centre of the envelope for Lim Keng Fatt of  7 Bond Street, Jesselton. Bond Street was later renamed Gaya Street during the post war rebuilding of the 1950s. Lim Keng Fatt was part of the anti Japanese resistance in WWll.

The front of the cover looks very plain. There is a red registered cachet. The registered mark is very faint but it has been pointed out to me that this is probably the Jesselton registered mark R3. Amazingly, this could be the second copy of this marking to be recorded. Proud gave only one sighting with the date of 27.5.19 in his book. It is ironic that the most valuable part of this cover is also its least attractive.
There is a very faint R within an oval with the number 1578 which is possibly an arrival registration mark of Sweden.
This is a philatelic item bearing the correct rate of 10c for foreign mail plus 10c for registration. Mr Thor Edward Quintinus Allard was a well known stamp collector in Linkoping between 1920 and 1960s. This is according to the dealer that I bought the cover from.  He collected widely and specialised in air mail covers. This was an item from his estate.
I really want to know more about Lim Keng Fatt if readers have any information. His name has been seen on philateic postcards and covers. Bond Street was the business district of prewar Jesselton. My guess is he was a middle man who benefited from having a knowledge of both Chinese and English. The philatelic covers were probably just a small side line.
Update I have taken measurements of the registered mark. It measures 46mm by 18.5mm as against Proud's R3 of 45mm by 18.5mm, very different from R2 or R4. The postmarks could be D6 or D8. I can not see even the faintest trace of BNB or Jesselton on all 4 postmarks. That does not matter.
R3 may not be so uncommon after all. There are 3 Oswald Marsh covers available to be bought, with similar looking registered marks.

Bond Street 1900s

Bond Street 1914

Bond Street 1930 

view from Bond Street

 present day Gaya street

Sunday market