OK, here's an example of an intercepting safety. It is the bar lying across the top of the lockwork. At the same time as the trigger lifts the sear out of engagement with the bent in the tumbler, it lifts the intercepting safety bar clear of the lug on the tumbler body. I hope this is clear enough from the photo.

Sorry for posting such a scruffy lock, I don't own this gun (yet!) so haven't cleaned it up or polished anything . It was simply the easiest gun to pull the locks off!

Also, just tested the Scott and the intercepting safeties can be heard clicking into position just before full cock.