Crime Fiction Alphabet: Letter K

I have signed up for a second year of The Alphabet in Crime Fiction, a community meme sponsored by Mysteries in Paradise. Each week she'll be expecting participants to produce a post featuring a mystery/crime novel or novelist related to that week's letter. 

Okay....somehow I got separated from the tour group and totally missed the letter J.  I'm not entirely sure what happened there.  But I've made a mad dash to catch up....and am ready to submit an entry for the letter K.

K is for Key.  That is The Key by Patricia Wentworth.  This mystery novel was first published in 1944 and is the eighth book in the series starring Miss Maud Silver. Miss Silver is a retired governess whose insight into hearts of children has given her the tools necessary to take up a late-life career as a private detective.  Her cases usually take her into the upper classes--often she finds herself helping out previous pupils or relations of such.  She also works closely with Scotland Yard Inspector Frank Abbott who has a great deal of affection and respect for her.  These are delightful cozy mysteries that remind me of Christie's Miss Marple. 

I have just started reading The Key, so I have no review to offer.  But I will give you the synopses from Goodreads and the back of the book:

Michael Harsch's long years of work were nearly at an end. The following day he was looking forward to handing over his precious formula to the government. But the next morning he was in no fit state to hand over the formula - he was dead.  He is discovered in the church with the door locked and the key in his pocket.  Of course the rector has a key, as do the sexton and the organist.  But it seems that those are all accounted for.  It looked like suicide, but Miss Silver knew it was murder.