How many authors are we still talking about 100 years after their debut?
That’s quite a century’s worth of accomplishments.
ENTERTAINMENT WEEKLY: Why do you think Christie’s novels and characters have endured for a century?

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JAMES PRICHARD:Very simply, it’s the stories.
She just wrote these phenomenal stories.
She came up with these ingenious plots.
The thing about great stories is that they last forever, and they cross boundaries.
Have you found over the years that interest fluctuates at all or is it pretty steady?
There’s always been interest.
I would say at the moment we have got perhaps more interest.
We’ve been doing stuff forever, but I think we are at a peak interest now.
Like everything really, there are peaks and troughs throughout time.
Now is a particularly interesting time, but we’ve never gone away.
Why do you think there is this peak right now?
Is it theKenneth Branaghfilms or something else?
It’s combination of a lot of things.
But I think the Branagh movie has worked on a different scale.
There is nothing to replicate the scale of a Hollywood movie.
For this enduring popularity, how essential do you think Poirot is to that equation?
Did his being the hero of the first novel play a role?
There’s no doubt he’s the key to the whole thing.
He was her major character.
He appears in almost half of the books.
He’s the only fictional character ever to have an obituary in theNew York Times.
[But] it goes without saying that Poirot would be nothing without her.
She did invent this character who still has this place in fiction.
To some extent, the two go together.
Are there titles that are consistently the most popular?
There are four or five which stand out and always have.
What is extraordinary is how it flattens off, but actually, almost everything sells to a level.
Then, you getMurder of Roger AckroydandDeath on the Nile.
Not all of them are writing in that vein.
Her legacy endures through licensing, be it screen adaptations, plays, even video games.
How do you field and make your decision on those requests?
It does tend to work a little bit haphazardly.
Some things come to us, sometimes we go to other people.
But what we always do, is we pick our partners very carefully.
That is the key to it.
I’m not a great filmmaker; I’m not a great play director.
I do understand what the essence of Agatha Christie is and what it needs to be.
I feel that Sophie was meant to be.
We love what she’s done.
She writes really interesting stories for Poirot, but it was complete serendipity.
Sophie is a massive Agatha Christie fan.
She’s a huge expert on the books.
She’s read them many times, but more than that she understands it.
She just had an idea that seemed to work and we went with it.
To some extent, it’s a gut feel.
That’s quite an interesting nuance.
That’s quite a big distinction and an important one.
Would you do it with any of the other characters besides Poirot?
I don’t know.
The obvious thing to do would be to do something similar with Miss Marple.
I wouldn’t want to leave Miss Marple out forever.
It’d be nice to give her a moment in the sun.
Besides Sophie, is there someone writing today you think is a worthy inheritor of the legacy?
I’m not sure.
There are loads of writers I admire massively.
What’s extraordinary about my great-grandmother is she sits head and shoulders above everyone else.
She is the bestselling novelist of all time.
There’s no one who sits above the whole genre in the way that she did.
How do you balance that public interest in her life with her penchant for privacy?
She kind of broke that by writing her autobiography.
She can’t have it all ways.
To me, it’s a privilege that people are so interested in her.
Greenway gets roughly 100,000 visitors a year.
That’s just extraordinary.
You do get a feel for her there.
There’s something about it that tells you something about her.
You mentioned before how Christie is right alongside Shakespeare in terms of popularity and sales.
We are therefore bracketed with Shakespeare.
It is putting Poirot as a part on the same plane as Hamlet and Macbeth.
We have serious people taking Agatha Christie seriously.
That’s incredibly humbling and rewarding.
Do you have a personal favorite book or adaptation?
I love things likeMurder on the Orient ExpressandAnd Then There Were Nonebecause they’re incredibly clever.
I was once asked what’s the best written Agatha Christie novel?
I have some favorites adaptation wise.
I lovedAnd Then There Were Nonethat we did with the BBC a few years ago.
It really showed a change in what we were trying to do.
[Writer] Sarah Phelps actually taught me about my great-grandmother’s work.
There are two particular things that she pointed out to me.
One of which is actually they are serious books.
She was very adamant that these were not fluffy little parlor game mysteries.
She took the crime seriously; there were consequences and all that.
What do you wish people thought about more when it comes to Agatha Christie?
I do think she is underestimated as a person, and particularly, as a woman.
She was a woman born in Torquay in England in 1890.
She lived most of the 20th-century, and she achieved all these things.
I don’t quite think that gets the recognition it deserves.
If I could leave a legacy, it’d be that she does move up the ranks of respect.
For too long, people underestimated her.