Thank you for your interest Peter.
Your observations are accurate. As I said, I had made some soft returns. Putting that aside it is the problem of the last line of para text which I was concerned with. That was the key issue.
It appears to be resolved now. I highlighted one of the last Para lines with expanded word spaces, Hit the range left Para icon and immediately all the text in the last line readjusted. That flowed on backwards throughout all the effected paragraphs over 4 pages. I have no idea what caused the problem.
Eventually I will probably learn how InDesign automatic setting works with para spacing. Until then I am happy that I have a technique that fixes the problem.
Thank you for your generous assistance.