Thanks to [this handy blog post](https://ariejan.net/2011/07/05/git-squash-your-latests-commits-into-one/) I found that you can use this command to squash the last 3 commits:

    git rebase -i HEAD~3

This is handy as it works even when you are on a local branch with no tracking information/remote repo.

The command will open the interactive rebase editor which then allows you to reordered, squashed, reworded, etc as per normal.