Is this the uniform of able seaman royal navy man 1920-1936. official photograph

[scrimnet]

BTW your chap didn't join the Navy because of a family association with the sea did he??.....his father perhaps or an uncle???

[medhist]

Not that I know of.  The only family connection with the sea was his great grandfather, Mariner,dead before he was born.

[r973g]

Nobody seems to have suggested a training ship/establishment.
A close-up of the cap badge might help to identify the other flag and give a clue
Ray

[medhist]

I've tried to upload a close up but site won't allow it.  If you save and then preview the image you could zoom in on the badge

[Stewart R]

Most of my attention has been drawn to the cap badge. I don't think the left hand flag is a white ensign because the quadrant that contains the flag of the union fills the whole segment but this one appears to show some white around the edges. I think therefore it is simply the red cross of St. George with some sort of motif, crest or a star in the upper quadrant. upon closer inspection of the other flag it looks suspiciously like a Wheatsheaf, maybe symbolizing that the Shipping line concerned were mainly bulk carriers of grain etc.  Just a simple case of finding the Shipping line that used this logo I reckon 

Stewart

[medhist]

Thanks for that Stewart. 

[PaulaToo]

Best I can do on the badge

[medhist]

Thank you.  I couldn't get it very clearly at all. I've been seaching for shipping line uniforms and for training ships which has also been suggested but no luck so far.  Thanks trying.

[scrimnet]

One dot on a cross of St George....rear admirals flag? Which retired admiral had his own shipping line? one of them must have....