Perhaps it is bad form to reply to one's own question but I can tell you that I have now recovered the Config.xml file that I wanted by restoring the whole of the C:/Users/Peter folder to my hard drive where I was able to alter the permissions and extract
the single file.
So, to restore one file of 249 kb I had to recover a folder containing 6,956 files with a size of 2.09GB and it took 50 minutes. This is not very "user friendly".
With more than 25 years experience in the computer industry, now retired, I can say that it was always my experience of backup and restore programs that installation of the program and doing the backups usually went well but restoring anything was always
a nightmare. As part of a system designed for disaster recovery, restoring of files is rarely done because disasters don't often happen, so the process gets very little attention from users and support staff.
I hope somebody on the development side at Microsoft will read this and take note.
Peter