I'm sure I am mistaken. Here is my experience with the tartan, in a nutshell.

I had a client order a kilt in this tartan. It would require a custom weave, of course, so I called the mill to order the cloth for the kilt. I was informed by the mill that they could only weave it with permission of "Madam McKerrell of Hillhouse" and they gave me her contact information. I passed that information on to my client.

A few days later he contacted me. He had called and spoken with Madam McKerrell for about an hour on the phone and said he had a very pleasant conversation. She asked him about his geneaology, and he gladly shared with her what he knew of his family history. Apparantly by the end of the conversation she was satisfied that he was a McKerrell descandant and gave permission for him to wear the tartan. However, he would be required to buy it from her. I think she already had some on hand.

In any case, he purchased the fabric from her, and then brought it in to me to make the kilt. He was very proud of the tartan and doubly so because he had to go that extra mile to actually obtain it. It just made it more special for him.