I absolutely hate the rewrites and plot embellishments that the newer TV scripts have done with the Agatha Christie books! It's not that they are just bizarre and unnecessary, they also have a weird ideological twist? which the original never had.
Eg just finished (re)watching "Agatha Christie's Marple: Why didn't They ask Evans". The original doesn't even have Miss Marple, ok fine, I get why they introduced her. But then, there' some completely random stuff about how the murderer, (lovers in the original) were brother and sister, long lost to their mother back in China, where the sister was sold as a "comfort woman", and now they are back plotting to kill the mother... huh? But why? why are you doing this? Most of the Poirot ones with David Suchet also have these completely random and bizarre ideological additions.
On a side note, absolutely obsessed with the 1980s shows with Joan Hickson (again)- she looks a bit like my grandma, loving the fashion, the gentle muted colours and body language.