May I just say one thing on this topic. I would just like to see this once glorious instrument restored to its former glory. Marcel Dupre once said that the Ally Pally Organ was the finest Concert Organ in Europe. He referred in particular to the magnificient Swell mixtures, amongst others. Another famous Organist GTB also spoke in glowing terms with regard to this instrument. Well, I'm not old enough to say that I've heard it live, but the recordings speak for themselves.
I only wish that everyone may work together to restore this instrument to its former glory, and provide a fantastic venue for Concert organ playing on a grand scale in North London.