I don't know if we are talking about the same show but in You tube, there are 3 seasons, each season is 12 or 13 episodes.
Actually, my mistake. I'm talking about the modern version--
this one.
The American DVD set that I have of this BBC TV show includes Series 1 and 2, so in my mind, it's just like one TV season in length. Again, such a shame it was cancelled, especially with a cliff hanger of an ending.