No luck. We did get a follow up lead via a phone call from a bird watcher about a week and a half after the plane attempt in an area that was feasible/reasonable for her to be and we got there within about two hours from where the lady saw a bird with "things on it's legs" but no signal was to be found.

I got another call about a peregrine 4 hours west of us, and sent someone to take a look and a bird was indeed there but the only thing on it was a leg band (no falconers gear).

We've given up an active search but will still follow any leads obviously.