Love that coat, Alice! I buy men's coats like crazy, then have a helluva hard time parting with them,'cuz I love them so much.... And I'm with everyone on the 50s' dating. I am thinking mid 50s, but I'm not familiar with all the variations on their labeling. But that "pass-through" pocket (called a "pistol pocket" which is a good keyword to use, or at least it used to be) and the raglan sleeves, along with the look of the shoulders, makes me think that rather than late 50s. I don't see many pistol pockets going on into the 60s; not that that is definitive, though.
Great coat, really, and vintage Harris Tweed is fabulous fabric. I had a ladies' HT coat from the 40s once, and it was almost like new! Alas, a lot of folks today don't "know" Harris Tweed and may not get the distinction between it and lesser-quality tweed. But when you get someone who knows what they're looking at, they will appreciate it. I sold a Harris Tweed coat to a woman in Australia once--literally cost as much to have it shipped as the price, but she was really keen to get a vintage Harris Tweed coat....