I have received a very prompt response from Duncan Cameron Clan Cameron Commisioner for Scotland. His response in full is as follows -

Dear Simon,

Tartans are always a disputed are and no doubt ex members of the Cameron
Highlanders and its later grouping would say Eracht is a regimental tartan.
However McLean of Dochgarroch in speaking to all the Camerons at a Culloden
lunch in front of Lochiel said it was ok to wear Erracht tartan. I wear
Erracht in various forms and some of the new weathered ones are great. Look
at the 'ancient and rare tartan book'

Interestingly the Cameron clan tartan is a Sobiesky -Stewart invented
tartan, the Lochiel tartan is for the famil,y so that leaves the Erracht and
the hunting tartans to wear.

Best wishes Duncan


The best that I can deduce from this is that Cameron of Erracht tartan is either unofficially official or officially unofficial depending on which side of the fence you sit.

Having recently ordered a COE weathered tank from Paul Henry if its good enough for Duncan Cameron it's certainly more than good enough for me. I also won't feel out of place at Achnacarry.