Probably not quite the right place to comment on the uniform but I would suggest that when the picture was taken, he was an acting petty officer from the supply and secretariat branch. Writer, chef or storeman. The Crossed anchors and good conduct badges are on his best, No1 suit so would be gold.
The supply branch all wore peaked cap, uniform but with black buttons and red cap badge until they were confirmed as Petty officer and then they would have worn gold buttons and gold cap badge. The seaman branch wore sailor suits until confirmed as Petty Officer but whilst an acting rate, would wear the sailor suit but with the crossed anchor rate insignia on the left arm.
Brian