Hello Duncan,
I did not personally harvest this wood. However it would be pretty easy to do so if I put some effort into it. There are at least 5 batches around the building where I live. This grows all over this region but picking out a good lot is not as easy as finding just any. You just have to pay attention for proper diameter and be lucky to split a piece that is not twisted up inside.
If I was going to harvest some I would look for some about stove pipe’s diameter , few knots as possible and straight as I could find. Finding some which is suitable may or may not take some time. However if someone offers up some good wood I am not going to turn it down.
-R