Greg responds...

Most of the research on Macbeth was done by Monique Beatty and Tuppence Macintyre. I did little or none myself. (I didn't have time.) Monique was my assistant (and is now a producer in her own right). Tup is a close friend and a Los Angeles Deputy District Attorney.

I know Holinshed was of some use. But I don't know what other books they used specifically.

Almost everything we did -- minus the gargs and Weird Sisters and the Mask of the Hunter -- was more accurate historically than Shaekespeare. (Not better, just more accurate.) Duncan and his father hired Gillecomgain to assassinate Mac's father. They rewarded him with Mac's title and with Gruouch. Mac eventually killed Gille and married Gruoch, adopting her boy Lulach as his own. There were some rumours that Lulach WAS his child.

Mac killed Duncan in battle, not while Duncan was a guest in his house. Mac ruled wisely for seventeen years and was overthrown by Malcolm Canmore, who was backed by the English. Etc.

I'm not 100% sure about Glamis, but I believe Macbeth's historical home was Castle Moray (also called Murray).