Thanks for all the helpful input. I have finally had a chance to dismantle, and examine closely these intercepting sears. In reality, the intercepting sear, in H & H pattern, parallels the regular sear, but it doesn't engage the tumbler at all(THIS IS A POINT I DIDN'T FULLY COMPREHEND); it is held just off of it by a small amount. So, the regular sear is the only one that has any engagement with the tumbler, NORMALLY, and should it jump out of contact, due to shock from gun being dropped, or from shock of firing other lock, barrel (double discharge), the intercepting sear stops, intercepts, the tumbler from moving forward, from firing the gun. Purdey pattern intercepting sear has a long arm lever that engages tumbler nearer to the top of tumbler. English boxlock intercepting sears, function similar to the H & H pattern, but the parallel sears are within the action body, of course, unlike H & H pattern sidelock. Finally, I now know how these puppies work, and how they look.