My git was refusing to create a branch from a remote branch but was error-ing with 'is-it-not-a-commit'as per this issue: Why is it not a commit and a branch cannot be created from it?
But as suggested by @SillyFreak it started working after I ran:
git fetch upstream refs/heads/master:refs/remotes/upstream/My-Remote-Branch-Name
However it only created a local branch (with new name as I prior deleted a error branch) without the tracking attribute.
When I try to add it with Git branch -u upstream/My-Remote-Branch-Name it says fatal: Cannot setup tracking information; starting point 'upstream/My-Remote-Branch-Name' is not a branch.
There are still some gremlins here - not sure what to try next