Wow, I never expected such a fast response to my post, and I knew it would be contentious. What I'm trying to say is that in my theory it was NEVER a MacDonald tartan but a district one pertaining to the lands over which they once 'ruled'. These lands were later aquired by the MacKenzies and the Earl of Seaforth added red and white lines to the Goverment tartan to reflect this district tartan. Of course there is no historical evidence for this and I'm just making an educated guess. I believe it was later on when they wanted to give the tartan a name that they called it 'MacDonald of The Isles' to reflect their one time domination of this district. Here's what the Register of Scottish tartans says about the MacDonald of The Isles tartan 'The design first appeared in the Vestiarium Scoticum and is different from earlier setts attributed to the Lord of the Isles or to any of the Clan Donald branches. It is not generally regarded as a clan tartan.'