Funny how many truth seekers in this particular arena don't like the facts being analysed to even the lightest extent, and abandon discussion for indignation at the drop of a hat. Debate is not about people agreeing with you, its about you convincing them with incontrovertible evidence.
So what we have is one feather of indeterminate age that may actually originate from the period of the twentieth century when we know IBWO still existed, from an area where we know IBWO still existed at the time. Doesn't advance the cause a whole lot.
Which still means no contemporary evidence of a large and highly visible, highly vocal, highly distinctive bird using easily recognisable, unconcealable nest sites that are re-used year-on-year despite all the equipment available to searchers. Basically because its not there.
John