Sadly it's not.
I found that while browsing around trying to find details on the walk. That ones just a 1.5 mile walk around the forest and falls of Campsie Glen. It's basically the path I mentioned that goes from Clachan of Campse to the viewpoint where the path on the map starts.
I met a guy a while back on a different part of the Campsies, he told me of a walk that Tom Weir used to do when he was young, he never knew the route but for some reason thought it started in Clachan of Campsie and may have possibly crossed over the fells towards Killearn, Dumgoyne or somewhere around there. But he wasn't sure why he had that idea.
If it really is the 6 mile round trip, that I read about elsewhere, then this can't be the case. I read that this route is now comemorated and supposedly used to promote the area. Campsie glen is a beautiful place and there is pride in the area to the Tom Weir connection but being so hard to find it's not really doing its job.
David.