I just bought a Westley Richards built with the original patent. I see five or six a year - on guns frm 20-bore to 8-bore!
The one I have is a 12-bore with black-powder proof and it is nice and tight - and shoots solidly with little flexing.
The top-lever of Westley Richards dates from 1858 but on certre-fires around 1863 seems to be the earliest I have seen examples.
The Purdey bolt came in in 1863 and the Scott spindle in 1865. Purdey bolts were first used with his first-patent thumbhole lever.
Later Westley Richards guns had both WR top-lever with bolt and Scott spindle and Purdey bolts.
Combintation sof Purdey bolts and scott-spindle operated via atop-lever emerge from 1865.