A blanket plugin called ‘Back End Restrictor’ works perfectly
Working perfectly! Thanks for your advice!
I must make clear.
mydomain.com > is the first install of wordpress.
Then after this:
Mydomain.com/install2
mydomain.com/install3
mydomain.com/install4
http://www.samuelowencarr.com/ << Link to the site, early stages of construction
Excellent. Perfect. Thanks 😀