Are you sure the two on the left are Webley screw grips ?
They look like they lock with a swinging bite that works off the top lever similar to the W & C Scott Triplex Lever Grip.
The gun in the center is a Webley A & W model boxlock, a screw grip. It uses the same doll's head and screw grip arrangement as the W & R model sidelock, which is what the Evans pair in question are. All screw grips used a rib extension of some type - doll's head or straight extension - because that's what the third fastener locked on, not on the threads on the spindle.
Again, those Evans guns are illustrated in the 1914 Webley & Scott catalogue at the bottom of page 20. They're Webley W & R models, and it's quite obvious. I'm beginning to think that you just want to argue, rather than obtain answers.
