I think they are probably a combination of deck and radio officers.
A curl on the stripe indicates a certificated officer and engineers with less that 3 stripes seldom had a full certificate.
And, as Harrisman says they are using glasses and just tooooooooooooo clean.
The gentleman with glasses is a purser, the white between the stripes can be seen. The one sitting on the deck is a radio officer, he has green between the stripes and a pencil in his pocket, only a sparks would carry a pencil.
Brings back a lot of very happy memories on this and the other mail ships.