...and yes we are going back into 'recent history' here....having scanned for more information....because the candy brothers had made a beeline for the 'tavern'....the one that Robert mentioned on his twitter site...they had then picked up on that Bristol signal...or rather deb mcd had done...she was then played a selection of 'bird song'....bird calls...to decide that the signal was most like a 'bullfinch'....she was to listen to the bird eating....to mistake its beak 'noises' for 'bird song'...to then compare that sound to the signal.....go figure:

https://www.youtube.com/watch?v=ZV5mSTe0Gs4