Thank you , it worked. 
But whilst in terminal I was also given two error messages. Maybe though these are unimportant, although if that is so then why would the information be flagged?
See below
Simon
The directory '/home/simon/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/home/simon/.cache/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
But whilst in terminal I was also given two error messages. Maybe though these are unimportant, although if that is so then why would the information be flagged?
See below
Simon
The directory '/home/simon/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/home/simon/.cache/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
That looks to be the same issue as described in https://forums.linuxmint.com/viewtopic.php?t=225876
Try deleting the .cache/pip/ directory and then recreate that .cache/pip/ folder with correct ownership/permissions as indicated in that forum post and see if that resolves the issue.
