Hi Ableach. Not sure if you are still on this forum. I have just come across the program for the festival concert.1966.
I am Mr. Bleach's son. Unfortunately, he sadly died earlier this month and I was fishing around here to see if there was any evidence behind the family myth that he was Jeff Lynne's Choir Master. It made me chuckle to hear he had a nickname. I'm not sure if it was an affectionate one or not

but it has made me smile anyway. Thank you for posting.
Just to correct your photo ID - my Dad (Mr. Bleach with an 'L') was on the right of the back row.