Thanks very much PKENEWELL, this works now.
I think your previous shorter version works as well.
Long story, but the issue was with the text file, as I discovered having issues with the initial code, once working, then not. It took me a while to figure it out. I was using Excel to dump the drawing list data into the text file and AutoCAD didn't seem to accept it.
Initially I tried the latest code, that did not work, then after working out the issue, your code did work and the previous shorter version seems to work as well.
Sorry if this wasted your time, but it may be useful for someone else.