Could someone explain the letter in "Mysterious Affair at Styles"? [spoilers]

Steelbeard

I've just finished reading Styles and I don't understand Poirot's answer to Hastings, in the final chapter, when Hastings asks when Poirot first began to suspect Evelyn Howard.  Poirot says that it was when he discovered she told a lie at the inquest about the letter.

I don't understand the significance of the letter at all.  Poirot noticed that Miss Howard and inserted a 1 in front of the 7 in the date line, to make it appear that the letter was sent on the 17th, and not on the 7th.  After Hastings asks him why she would do this, he says "Why does Miss Howard suppress the letter written on the 17th, and produce this faked one instead?  Because she did not wish to show the letter of the 17th.  Why, again?  And at once a suspicion dawned in my mind."

Poirot elucidates no further.  What letter of the 17th did she not wish to show?  Was there another letter Mrs. Inglethorpe wrote to her?  When?
Back in the chapter about the inquest, the facsimile of the letter she faked is shown, and Hastings remarks that he and Poirot had "already seen it."   When was that?

If anyone could clear this up for me, I'd be appreciative.

GKCfan

***SPOILERS***

Regarding the "already seen it remark," I can't find any reference to Poirot and Hastings reading it– unless they saw it in the despatch-box, but my guess is that a reference to  Miss Howard showing them the letter was deleted at some point in the editing process.


As for the "17th" letter, Miss Howard couldn't say that there was no letter (though she could've claimed it got lost in the mail) because Mr. Inglethorpe had probably heard through the investigation that Mrs. Inglethorpe had sent Miss Howard a letter that day (remember, that point was made publicly on at least one occasion, so everybody knew there was a "17th" letter).  Based on the fact that Mrs. Inglethorpe found her husband's damning letter addressed to Miss Howard (and locked it away where he couldn't get to it), she probably wrote a letter to Miss Howard along the lines of "Dear Evelyn, What the heck is going on?  I just found a letter my husband was writing to you?  He thinks I'm going to be dead soon?  What on earth did he mean about the bromides?  Are the two of you having an affair?  If you don't explain yourself very soon I'm going to call the police.  Sincerely, Emily"  Miss Howard certainly couldn't show the police that letter, and she'd heard from Alfred that the police knew about the "17th" letter.  Only one thing to do.  Burn the real "17th" letter because it could get her hanged, and then find a duplicate letter– and putting a "1" in front of the "7th" was the simplest and seemingly elegant solution.

Steelbeard

Very nicely explained.  It makes perfect sense, thank you.  I reread a great deal of the book looking for some reference for Poirot and Hastings having already seen it and thought I was going bonkers.  It just isn't there.  As you said, probably edited out.  The copy I have is from Harper Collins, and it includes the original reveal with Poirot in the courtroom, which Christie's editor asked to be rewritten because he didn't find it convincing.  There must have been a lot of that going on, especially since this was her first novel.  If I were an editor, I'd have been much more unlikely to ask for rewrites later in her career.  

GKCfan

You're welcome!  Thanks for posting on the discussion board!  It's been kind of slow here lately, and the more people who contribute, the better!