Aye, as did my own clan from about 1779 until 1953 when General Sir Gordon MacMillan (father of our present chief) proved up his claim to be MacMillan of MacMillan and Knap.

In those clans where the chiefship has become "lost" (in other words where there was a known chief at sometime in the past, but the present claimant is unknown) then it is perfectly correct for a clansman to wear the badge of the last known chief.