Please help identifythese British WW1 uniforms

[JOVO]

Hello, please can anybody help me identify these two uniforms in the attached photos ?
They are two of my great-uncles who were in the British forces in WW1. But I can't find any confirmation of their regiment, where they served, etc.
Any help or ideas would be very much appreciated.
cheers
Gareth

[Jerry B]

I can only point you in the right direction, not give a full id. The first looks to be navy and not an officer as they have braid on the peak, not merchant marine but a private liner company I think, similar to white star or P&O but it is not either of them and the second looks to be a fusilier regiment, though not a royal one as they have blue collars, so before they became royal or never did.