Thomas just beat me to it... but
The re-enactor is supposed to be aGrenadier, not a Coldstream. ( Beware re-enactors : they are often very good, but they are NOT original references . Where's his moustache ? He has a P.53 3-band Enfield, rather than the P.51 Minie which he should have , etc ))
The Coldstream had the Garter Star , not the Royal Cipher , on their collars and packs. And the turnback badge was a Regimental pewter button on a white embroidered star.
I know you only want details to paint one figure, but you will never regret investing in books. They discuss the whys and wherefores, and give the deeper picture .