There is a Primus No. 1 available locally, but the tank legs, etc are painted instead of the natural brass I am used to. Additionally, it appears that the pump cover is slotted instead of threaded. I could not find one like it in the reference library, and am curious as to whether I should grab it.
I am no expert of the marque but have yet to see a domestic stove with brass legs as original. Brass would be too good a conductor of heat, so the legs would get rather too warm. All my fixed leg stoves have steel legs, sometimes tinned to protect against rust. Collapsible ones have had steel or alumin(i)um. Your picture shows a recessed filler point, which suggests more modern rather than older. The Primus name is in raised lettering, which is a bit unusual. I am wondering whether the stove might have been made elsewhere under licence from Primus. Don't ask me why, it's just a feeling. I cannot enlarge the picture sufficiently to see what is printed on the Primus tag. Hjorst, Bahco, or Primus Trading would all help to identify a date period. Are there any number /letter codes on the underside, or on the riser or burner? The final two of six digits would indicate a year, or letters in a circle underneath can be checked against the Primus dating chart. The filler cap looks very 1960s. Just my opinion - someone more sensible/knowledgeable/opinionated will be along soon.....
This looks like one of the South African made Primus stoves from the early 1960s. The recessed filler cap hole, knurled airscrew and filler cap with a slot in the top were advertised by Primus around 1961/2. The steel tank with raised embossed Primus logo was a feature of those made under license in South Africa. The spirit cup is also the AB BAHCO version, used between 1956 and 1964 only. The stepped legs that follow the profile of the tank are identical to those used on Swedish Primus 1's and 5's from the same period.
Looks like Primus Popular? https://classiccampstoves.com/threa...-1-and-5-in-new-metal-launch-info-1959.39575/
Definitely South African made, it will have a steel fount. I have one the same and another with small variations. Probably not that common and a good working stove.