Who's the best Poirot? Let me give you a clue

Elementary, my dear Watson. It is, of course, Sherlock Holmes.

Since his creation in 1887, Arthur Conan Doyle's doyen of deduction has been portrayed by more than 75 actors on stage, screen and radio.

Even now, he has three different guises. There's Benedict Cumberbatch's brilliantly geeky, award-winning interpretation in Sherlock, Jonny Lee Miller who has been a mega-hit across the pond in Elementary, and Robert Downey Jnr who has revived the character on the big screen with an intoxicating mix of scruffy wit and quickfire comedy.

Contrast this with another great TV sleuth, Agatha Christie's legendary Belgian detective Hercule Poirot.

The likes of Albert Finney and Peter Ustinov may have twizzled his famous moustache in the past, but for a whole generation of viewers, David Suchet quite simply IS Poirot.

Since his first outing in 1989, Suchet has adapted every single one of Christie's stories.

On Wednesday, we saw the beginning of the sunset. The Big Four was the first of four two-hour episodes which mark Suchet's swansong.

The other three, Dead Man's Folly, Labours of Hercules and the poignantly-titled Curtain: Poirot's Last Case, will be aired next month.

It's a remarkable achievement from an under-rated British actor who has written his name into our TV folklore. The unmistakeably dainty, almost constipated penguin-like gait, the uppity, fussy mannerisms and the Hitchcock-like body suit have been with Suchet for more than a third of his 67-year-long life.

It's hard to see where the actor ends, and the character begins. It's only when you check out Suchet's other, amazingly varied body of work that you realise how un-Poirot-like he actually is.

But here's a slightly trickier trivia test. Hands up if you know why Ludlow played a small but important part in helping to land Suchet the role. I bet that one's testing your little grey cells . . .

Well, it was after appearing in Tom Sharpe's comedy series Blott on the Landscape, which was filmed in the south Shropshire town, that Suchet was recommended for the part by Christie's family. The rest is history.

Suchet's Eureka moment came about eight years ago. By then, he'd starred in about 50 episodes, and realised he was approaching striking distance of completing the canon of 70 Poirot stories. He soon made it his personal ambition.

It's been touch and go. A couple of times, ITV has toyed with the idea of cancelling the series after disappointing viewing figures.

Happily, particularly for Suchet, the clamour for Poirot's return after a couple of two-year hiatus periods was always too strong.

And Suchet deserves his moment of personal triumph. Some actors fear being typecast, but he's never let his defining role stand in the way of a separate, thriving stage and screen career.

So the end of an era has begun. Sherlocks may come and go, but it will be a brave man who tries to follow in David Suchet's footsteps as the one and only true Hercule Poirot.