Wow, MB, what a FABULOUS farewell salute to Clarice! I've been watching 1966 episodes in the past weeks and really enjoying her performance. Unfortunately, I don't have what I think must be her very first episode, which I believe had her visiting Burke Devlin immediately after Bill Malloy's death--I'll have to check the DS Memories episode guide to see if that is the case.
That scene with her and Blair was so moody and evocative. Mrs. J telling Blair she is convinced that there is a curse on Collinwood. It's the same episode in which Julia comes staggering in from her little constitutional in the woods moaning for Tom... one of the top ten episodes of all DS, in my book. Grayson and Joan had some fabulous scenes in that, as well...
As for why Clarice left, I'm not sure that she had a contract for DS after Minerva's death in 1897. She only had a couple of episodes during Leviathan, nothing in Parallel Time (she would've been great casting for Hannah Stokes--I wonder whether she was simply unavailable at that point), and then that wonderful string of episodes in 1995.
I don't know when she started working on Secret Storm. Around this time, as well, she began her new career as a writer, in which she found a great deal of success.
There is a letter from her in that fan-published book of letters from the DS actors to fans. She thanks whoever had written to her and asks if fans can write in asking for more of Mrs. Johnson... kind of breaks my heart to read that.
G.