Probably because ITC sounds similar to ITV, it makes me think of the Agatha Christie IP, especially the brilliant, just brilliant adaptation of her books about Hercule Poirot with David Suchet in the titular role.
Regarding Miss Marple: Not really good adaptations, but a favorite of mine in my youth were the Miss Marple movies with Margaret Rutherford as Miss Marple. Later on, I much more enjoyed Joan Hickson as Miss Marple. I guess she is for the franchise on Miss Marple’s side what David Suchet is for Hercule Poirot.
But I also did enjoy other interpretations of both of them and, of course, read all the books.
I also do love the tribute to Agatha Christie The Unicorn and the wasp.