The gauntlet cuffs were introduced in 1868. The facing-coloured slashed panel cuffs in the photo were initially worn with the double-breasted “Crimea” doublet with Inverness flaps in 1855, which also had diamond-shaped buttons (all very Highland-Gothic). That mirrored the double-breasted tunic introduced for British infantry at the same time, which had slashed panel cuffs similar to what the Guards wear today on their No1 Dress ceremonial uniforms. The DB doublet was shortly after replaced by a single-breasted version with round buttons (as per the photo), which lasted until 1868. That year facing-colour gauntlet cuffs were introduced, plus a red collar with 2 facing-colour patches at the throat. Collar badges were discretionary, according to regiment. The rest of the army wore a new tunic with red collar and facing-coloured patches, facing-coloured pointed cuffs with white trefoil braid decoration (as per the film Zulu Dawn). Red was replaced by scarlet in 1872 for rank and file (stands out better for being massacred in, don't y' know old chap, what what !)