To add to ycaso's information.
My own PC is in for repair and data recovery so don't have all my data to hand.
The two sitting are members of the Royal Marines Light Infantry (RMLI), the badge is clearly showing the Globe & Laural surmounted with the Bugle of the Light Infantry.
The cross belt of the soldier in photo 2 is The Inkerman silver whistle and chain worn by all Warrant Officers Class II, Colour Sergeants and Sergeants of all Light Infantry Regiments that include the RMLI & Rifles regiments. As the name suggests, the honour of NCOs wearing an officer's whstle & chain dates back to battle of Inkerman when the 68th Foot (Durham Light Infantry) drove the russians from the field at baynet point and significant losses to officer ranks meant the regiment's NCOs took over the control of the battle.
The badge of the light infantry regiment is always shown on the cross belt and although some look similar and I haven't been able to enhance the picture it looks like it could be a RMLI insignia. Making him a colour sergeant in the RMLI.