The 'Invincible' range was produced by William Newman & Son coming in a number of strengths and guises. These being - single action, with or without check, double action, with or without check, shallow box, single or double action, with or without check and finally a water tight version for wet areas, with or without check.
You can see in this repair the pin was offset due to wear and therefore not closing correctly against the door frame.
And finally below an 'Invincible' I found on the web.