Stay logged into account on restart

System Preferences > Users & Groups > Login Options. Set "Automatic login:". If you have Filevault enabled you can't override signing in.

Ok here goes.

You can’t.

I wholeheartedly agree with Aperture though I transferred all my shots to Photos in their original projects, now as albums. Less functionality and annoyingly sends me memories but hey what’s loss of expertise and £50.

Re your original question you would not only need to protect files but somehow also your calendar, notes, contacts, emails, turn off keychain and delete all autocomplete passwords.

If a burglar took it, it would not be in your home, and surely all he needs to do then is restart it?

All my caveats still remain. If you do that keep it in a safe.

It’s why I suggested he can’t do it. If a user asks how to shoot himself in the foot I’m not going to show him where the bullets are

That is very different than "you can't".

Thanks for that

You're welcome.