One of the professors here is disabled. She installed PVC doors so that she
could easily get in and out of her house. They started to harass her about
it, but I believe she just paid the fine and kept her doors. It was in the
times last year.

The building control approved documents has many provisions for
disabled people. The disability discrimination act made provisions for
appropriate and practicable adaptation of older commercial buildings.
I'd be surprised if conservation area rules didn't have such
provisions, where it was relevant to a disability.

Do you have a link to the Times article?

Realistically councils do sometimes get on their high horse and
prosecute/persecute when a more understanding approach would be
appropriate.