This chap definitely ticks many of the 'Walt' boxes but are you sure he isn't dangling a GSM and and an ACSM (Accumulated Campaign Service Medal)?
The ACSM ribbon is near identical to the GSM post-'62 one except it has a thin yellow stripe running down the middle.
I was once accused of being incorrectly dressed by some dripping for the ears Cranwell brat because he thought I was wearing two GSM's rather than the GSM and ACSM medals that I've been 'lucky' enough to spend enough time away to gain.
Further more he could serve on an infantry battalion and be a S/Sgt if he were from one of the corps on attachment. If he were REME for instance that could also explain his youth yet relatively high rank (for his age) attained.
Of course if he is pretending to be an MBE for personnel gain then that is a criminal offence and one that is easy enough to discover by searching for his name in the London Gazette.