Saw this on Talking Pictures channel (UK TV - old films & TV shows). It was broadly faithful to the book, and indeed so was the Rupert Davies version (BBC - early 60s), which by coincidence was on the same channel recently, a further rerun of that series.
This story takes a while to unravel, in this version, the Davies story told the same plot in half the time!
Cremer though plodded slowly about, making witnesses uncomfortable, and using little tricks to discover a few secrets they'd like to hide. HOWEVER, it seemed quite unbelievable that he'd almost reached the end of the show before talking to the victim's family???
The victim was a maid, working for an old lady who was part of a formerly rich family, the maid had been poisoned, on a night when the family had gathered for a birthday, but was she the intended victim?
This version introduced an extra character, a gardener, who said very little to anyone (so didn't help the story much?!), and had also featured a clumsy seduction attempt on Maigret, which took quite some time to play out, and added nothing to the plot.
The acting is very good in this French series, and I can bear the subtitles, but frankly the stories are almost all padded out to a tiresome degree, and could do with being half an hour shorter (not almost 2 hours, which just drags).