I cannot believe what I am reading in this post, is it a joke ?
It is blatantly obvious the wheel was put in incorrectly with the brake plate not secured in the slot.
How anyone could do that beggars belief !
There is no other way such damage could occur.
I suggest that you let professionals work on your Morgan to avoid causing yourself or others serious harm.
By the way the disc is a spot on conversion and benefits those of us who are serious users. Yesterday I did 15 Hill Ascents in my M3W at Prescott Hill Climb raising money for the BloodBikers. The Disc brake far outperformed the drum.

Morgan Family 1929 ( KTW 1100cc )
Morgan S/S 1934
Morgan F4
M3W 2012
Morgan +4 T 1991