"You almost succeeded in confusing Poirot!" says our favourite meticulous Belgian detective to the culprit in The Double Clue, revealing two important things – he often talks about himself in the third person, and he is never confused for long. Hercule Poirot's brain, you see – under that sweep of thinning blackened hair – is bigger than yours. He misses nothing, and 65 crimes in (this complete box set, out on 15 August, includes all episodes so far) he is still as sharp as his three-piece suits.

The series started in 1989 with The Adventure of Clapham Cook, which set the tone – seriously played, but with flashes of humour. On a trail in the Lake District, Poirot is furious with the beautiful countryside (he has to tiptoe through cowpats). It is, he says with contempt, "a wasteland!" In these early episodes, David Suchet is still feeling his way in the patent spats of Agatha Christie's hero. It is a credit to Suchet that his willingness to give so much of his career to this man – self-regarding, brilliant and often irritating – has produced the definitive Poirot.

The hour-long episodes are delicious morsels, with beautiful art deco architecture, perfectly paced sleuthing and Captain Hastings, the comedy sidekick and dishy English gent. In the moving The Chocolate Box, we get to see the young Hercule; others, such as The ABC Murders, are just plain thrilling.

Five Little Pigs, the first of the lavish feature-length, all-star episodes, was shown in 2003 (in this, as in others, the plot has been tinkered with but not detrimentally). It gave the series a boost, though recent episodes have become too tongue-in-cheek for me. Last year's Murder on the Orient Express changed tack totally – it was wonderfully dark, but took itself too seriously. Perhaps they can't win.

Anyway, it did bode well for the few Christie stories still to be filmed (I hope). For Poirot, says his friend in one episode, "a life without mystery would be like roast beef without the mustard." The same is true for his fans.