Change-ringing is a practice very peculiar to England. The bells are rung in sequence, then rung again with the positions within the sequence re-arranged, hence "change". There are a couple of towers over the border into Wales and Scotland set up for change ringing, but they are very uncommon there. Continental bells are tuned very differently, and controlled differently. The carillon, arranged to play tunes using an arrangement like a keyboard, is much more common across the Channel.
In England, both Church of England and Roman Catholic churches carry on the change-ringing tradition. Ringers are not what you would call professional, but usually receive payment for ringing on special occasions such as weddings, in the same manner as the organist and choir.
There seems to be some confusion about which peal was the long (10080 changes) one. I would tend to believe the version in the ringing room.
The names of peals relate to the types of changes made during the performance, and might also depend on the number of bells involved. I can't say I can follow the pattern of naming.
"Double Union Triples" is described at
https://complib.org/method/28297 but whether this is the same version your ancestor was heavily involved in is open to conjecture.
Many towers have fallen silent in recent years. The strain of heavy bells moving around has taken its toll on many, and a few have fallen to legal threats by incomers who don't like being woken before lunchtime on Sundays.