WO1 (GSM) WDG 'Billy' Mott OBE MVO, Welsh Guards....A garrison sergeant major (GSM) in the British Army is the senior warrant officer of a garrison and holds the rank of warrant officer class 1 Military Mess Dress, Military Dress Uniform, British Army Uniform, Military Dresses, Military Uniforms, Military Guard, Military Ranks, Military Insignia, Military History