There are two and both excellent. The original in 1967 was so riveting that in Australia everyone went home on Friday night just to watch it.
Watching it again now, I’m find it a little overacted as if it were meant for thestre not film. But still gripping.
I loved the 2nd one starring Damian Lewis and Gina McKey just as much at the time it was released but must watch it again to see how it bears up.
As for the books they are a masterpiece.