I could also call this the 4-5-9-10 crossword, for it only uses words of that many letters from Agatha Christie titles. The fun would be to do this without Google! Here are the clues:
1. A Tommy-Tuppence mystery with two letters
2. Currently celebrating the 63rd year of a record breaking run
5. Poirot in the news/ murder in the __
7. Oh the foolishness of the departed fellow!
9. Describe the cyanide
12. While this lasts, you have a collection of short stories
13. Tommy and Tuppence end their career… And so does Christie, in a way.
15. Who can remember?
16. One, Two…
1. In the beginning, there were ten little niggers; in the end, there were __
3. Be there if you want to catch the 4.50
4. Investigator Parker
6. Why didn’t they ask, wonders a dying man.
7. Tommy-Tuppence again, and this time it’s about a passenger.
8. Mystery at L/ finished with ale
10. The Unexpected causes trouble
11. Poor horse, it was so… But wait, was it about the horse?
14. Here’s your clue/ the train was __
And here’s the solution: