He has it absolutely right but let me expand this, because it seems bizarre to those of us used to 20th C rank badges.
The rank badges were indeed worn on both sleeves, a simple diagonal bar, not the chevron we now expect. They were aurore or gold, again as above, but just above the cuff. Low forward, highest to the back seam. How odd for us.
Right. Long service recognition. Ah, now they are the chevron we would instead now expect for rank, but these are left sleeve only and they are point up. (yes, I know USA use that, but I have never understood when). One for ten years, two for 15-20 and three for 20-25 years. You would have to be pretty dim or illiterate to merit three chevrons still in Aurore and not be worth switching to gold, as an NCO!
It is tricky, but let us say you are a sergeant with more than 25 years service (lucky blighter!) you would look rather elegant with two diagonal gold slashes above both cuffs and three gold chevrons above the elbow of your left sleeve.
Simple…unless we are talking about units that had pointed cuffs of course. ARRRRRRRRRRRRRRRRGH