Yes, you and ken are correct. It is a snare. The loop went over the trigger pan and was attached to each end bar that springs out. Apparently to catch and hold a rabbit by the leg. Had a better look today and the is the remnant of a brass wire on one end.
Also spoke to another collector who knows far more than me, straight away he told me what it was, approx age, 1920s and value.
Thanks all for your input.