I restored a 10b SLE by Clabrough a while back and that had the same ejector system: basically a 'hold back' mechanism, similar to Boss and Coggies.
I searched for a suitable patent to attribute it to as the action was engraved 'Patent Ejector' but there was nothing I could find in the Claborough name. Finally I had to assume it was the same system as used by C&H in nearly all their guns as it is functionally identical.
The patent is
E Harrisons no. 11550 of 1888.