Hi Konrad - nice set you have there. To expand a bit on what Craig and others have said, you probably know that this set of 13 figures (48004) was one of four Limited Edition sets - the others being set 48005 (4 piece additional pipers), 48006 (5 piece Colour Party) and 48007 (2 piece Escort to the Colours). They would look even more terrific, should you be able to add in those other sets!
The Cameron Highlanders were founded in 1793 - but in 1873, Queen Victoria directed that from that time on, the unit's original dark green facings would be replaced by dark blue - as it would now be a Royal Regiment - to become 1st battalion, The Queens own Cameron Highlanders - the County Regiment of Invernesshire. So your band can only date from then on. As Craig rightly told you - they were amalgamated with the Seaforth's in 1961 - and changed title. Today they survive in but name only - as the 4th Battalion of The Royal regiment of |Scotland. Further clues to dates show in the tunics - as these are single breasted and have gauntlet cuffs - introduced around 1868 - so you can discount anything earlier than these dates.
Other clues show in the number of battle honours depicted on the drums - though you do have to be a bit careful here - as painters often squeeze in what they can, rather than go for absolute accuracy. Looks like your guys have around twenty or so shown on the drums - so a comparison with any real pictures of the band you may find, might give you a clue as to the era. Note that the drums still appear to have have the rope tensioners - another clue to date.
I think that you might be on safer ground - if you were to ask Britains if they had a date in mind for these issues - as they might well have some pictures that they worked from with these special editions. They were produced relatively recently - in 2008 I believe, to commemorate the 25th Anniversary of Britains production of Limited Edition sets (1983-2008).
I would have no problem with a date around the 1950's for them, though they could be earlier - as the basic tunic changed very little after the 1881 reforms.
Anyway, hope that helps - johnnybach