I have no idea Susie, a chap found it when clearing his late mothers belongings and was equally intrigued to know more. It is quite likely that this could be related to some form of coastal or marine activity. I thought of the customs service. Cant make out what is on his jacket cuff.

No, and also I can't make out what his on his hat apart from the top symbol which looks like a crown.

I think that generally people like coastguards and customs have a hat which is white on top, not black, but then this is an old pic - do you think around 30s or 40s?

Not sure but the Bike maybe a clue for dating purposes, looks like it has racing handlebars, a dynamo powered front light. 

They look like Royal Navy Petty Officer badges.....and the 'emblem' on the sleeve looks like something attached to the bike handlebars rather than attached to the sleeve?

Hmmm ..... I didn't think that the badge on the hat below the crown looked like an anchor,  but it could be an embellished anchor, so you may be right Astro

Pity the pic isn't clearer

Yes you could be on the right track Astro. I wonder when that collar style was in fashion? I just found this online which looks quite similar to the cap badges shown, They are the Royal navy auxiliary service.

and a bit like this?

This is Royal Navy ca 1940

And this:

Could that be the same insignia on the sleeve?  This is the Royal Navy Patrol Service sleeve badge

Yep, his collar isn't bad either. 

Single breasted jacket in that one, but the hat badge and sleeve insignia looks similar.

Maybe it isn't single-breasted, but the angle he is sitting at.

Well done Astro for putting us on the right track.  I ruled out RN after I didn't think it was an anchor on his hat, and it wasn't wings for Air so I was stuck.  Thought it might be merchant navy, but well spotted astro.

What a pity Dame Vera isn't a member on here, she could have told you in a second. She was very popular with the services, around about that time.

Wow, Thank you SS, that was really helpful and I will pass on to the person concerned who I am sure will be very grateful and probably intrigued.

Well done SS! I was on the wrong path. The photograph reminded me of a cousin who was a Chief Petty Officer in the Royal Navy, and the badges looked similar. Always nice when a poster gets the correct answer.

So was astro really wrong?   Where is the proof that this is the Queen's Messenger uniform?

Can SS show us a picture, especially given that the sleeve insignia and the cap badges look very much like the Petty Officer uniform seen in the pictures posted?