I would be interested to get your views on the principle differences between the Beesley/Purdey self opening (SO) action and the Atkin self opening action, Dig.
As I understand it, the Atkin SO incorporates improvements to the ejector system and to the cocking pads. It is clear from the photographs of the two actions you posted that the Atkin has an additional ‘spur’ located outside of the bridle. What is its purpose?

It would appear that the Atkin action improves the Beesley/Purdey design and makes it easier to operate, so well articulated by Gough Thomas, of course.

Thanks

Tim