I have yet to see any concrete evidence to suggest that there was even a drone! Even in this day and age there should be far more videos and photographs especially at LGW where many gates and walkways cover a wide view of the airport.
Was this blown way out of proportion by closing the airport for such a long time? Of course it was!
I have a strong feeling that ground staff confused a bird with a drone on several occasions after the initial "wrong" drone report came through! The media obviously didn't help with their usual style of reporting. This media added an external pressure to LGW management and they felt they had to be seen to respond by making such a horrendous decision in closing the airport!