Miss Lemons filing system explained – unusual correspondence

When I returned to the office, Miss Lemon was writing on some cards.  What I could glimpse looked like gobbledegook to me.

“The agents have asked that you call on them tomorrow at 10 a.m. to go through the formalities,” she said. “The terms are very reasonable.”

“Thank you, Miss Lemon.” I was still staring at the cards on the table. “What were you writing? Is this the famous filing system in action?”

Miss Lemon removed her pince nez and gazed at me assessingly.  She moved as if to cover the cards with her hands, then drew them back.

“It is my own form of code. Forgive me if I seem so protective of it. M Poirot always drove home to me the need to keep my system secure. He did write, however, that you were to be trusted unreservedly. Even so…”

As she considered, I was beginning to be irritated by her lack of faith in me, and wondered what kind of working relationship we would have. After all, if there was anything hugely sensitive to be found in her precious system, I could keep my mouth shut. Finally, she resolved.

“Have a look at this, Captain,” she said, handing me a card. “It’s an appointment card I have coded for you.”

JBFRB  QBMBWFJ : F.E.
0001 0110 / 1001 / 0001 1001 0100 0011
0001 0000 F.K.

I stared at it. “Appointment for what? For whom?”

“For you. It confirms your appointment for tomorrow morning.”

I laughed. “Well, I’m glad you didn’t send it by telegram,” I said. “How does this code work?” She showed me another card.

“I use a simple enough system for straightforward matters.  For anything to do with this flat, say, a new alphabet is produced based on a key word – in this case, ‘flat.’ The individual latter in the word ‘flat’ are placed at the front of the new alphabet, and the rest of the alphabet follows them. The normal alphabet is then written underneath it.

F L A T B C D E G H I J K M N O P Q R S U V W X Y Z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

So, to decode your appointment card, find the letters in the top row and write down the corresponding ones from the row below. Try it.”

Miss Lemon handed me a pencil and a sheet of paper. It did not take long. Underneath J was L, underneath B was E, then A, S and E again. ‘Lease renewal’, I read.

“And FE?” she asked.

“AH – I guess that is me. But those numbers make my head spin. What are all those 0s and 1s supposed to be?”

“They represent the date and time of your appointment, using our own form of binary code for the numbers 0 to 9.” She took my pencil and scribbled on the card:

0000  0001  0010  0011  0100  1010  0110  0111  1000  1001
0        1        2        3         4         5         6        7         8        9

I looked again at my appointment card. “1…6…9…1…9…4…3… Why, that’s tomorrow’s date!”

“And the time?” Miss Lemon prompted.

“1…0… A…M…   I am sure this is all very clever, but what is the point of it? Why spend so much effort on such a trivial matter that could be written down in seconds?”

“This was just to show you how it works. Clearly it would be ridiculous to encrpyt appointments such as these. In any case, a simpleton could work it out.”

I was not sure that I liked the implications of that, but before I could say anything Miss Lemon continued:

“With more complicated examples, my encryption goes though a few levels of change that would be very difficult for someone to crack. It is not so difficult for me. I can work out these codes in my head, I am so used to creating them. I can read them as if they were poems.”

“But no-one else will be able to!” I protested.

“And that’s the point!” Miss Lemon retorted loudly. “Our client’s confidential information must be held in a way that protects it from others.  M Poirot was delighted with the way my system was developing. He had concerns at the start that it would overshadow my main duties, but by the end he was happy enough.”

“But could he read it?” I asked.

“I did explain it to him, but he never had cause to use it. I was always there for him.”

She sat down behind her desk.

“What do you want me to do now?”

I didn’t know. I would have liked nothing better at that moment than to pull out the drawers of the filing system and hunt for the cases that I had worked with Poirot on, if only to see which bits had been filed away in the Colossus. However, Miss Lemon had hinted that the coding for confidential cases was far more complicated, so I resisted the temptation. In any case, our job was to put Poirot’s affairs in order. Where to start?

I decided that we should work backwards. The most recent items in the whole flat were the unanswered letters.

“Those letters …”

“Yes?” said Miss Lemon eagerly.

“I think we should reply to them. Something along the lines of ‘Poirot has died, sorry, cannot help‘. You know the kind of thing.”

Miss Lemon looked shocked, bewildered.

“I can’t do that. I would not know what to say to all these different people. You must tell me what to write. M Poirot used to dictate all his correspondence.” she said, reprovingly.

Now, Poirot had mentioned that Miss Lemon was one of those people who take everything literally, lacking the imagination or will to embellish anything. ‘But she has a fine mind,’ he had said. ‘She is never wrong.’

“What’s in those letters, anyway?’ I asked, somewhat tetchily. “Maybe I should read them first.”

“There are two from what I can only describe as cranks talking about world-wide conspiracies – at a time like this!” she replied. “There is one form a countess living in Ireland who believes her family are trying to poison her, one from a woman in Brighton who has lost all trace of her son, one from an old lady in St Mary Mead wishing to meet him … and then there is this.”

Frowning slightly, she pushed an envelope across the desk to me. There was no address on it, just Poirot’s name. I opened it.

BY HAND 
London WC1
July 12th

Trafalgar 1212

My dear Poirot,
Thank you very much for the observations you made during our discussion last month. Having investigated further, I have spoken with my superiors and they have suggested that I follow up one item in particular with you.

When you return, please ask Miss Lemon to call me and arrange a mutually convenient time to do so. 

Yours sincerely

J G 

Miss Lemon was looking at me expectantly, so I re-read the letter, but I could find nothing unusual in it.

“It doesn’t tell me much,” I said. “All a bit cloak and dagger, maybe-”

Miss Lemon interrupted me.

“It is a strange letter.” she said firmly.

“In what way?”

Miss Lemon began to enumerate using her fingers.

“1. If M Poirot had arranged a meeting with a new client he would have told me.
“2. When I found this letter it was in the middle of this pile. If it was delivered by hand, who picked it up from the letter box? It was not me. M Poirot had already died by then. So, how did they get in?
“3. The letter mentions me by name. How did he know my name?”

“Perhaps Poirot had mentioned it,” I suggested.

“He would never do that to a new client that I had not met. Finally, 4. Notice the T in Trafalgar. It is very singular. My typewriter has an identical flaw with its capital T. This letter was typed on this typewriter.”

I stared at her, my mind racing.

“You mean someone broke into this flat to type a letter to Poirot?”

“Or was shown in.”

“Apart from you, who else has a key?”

“The landlord. and of course M Poirot had one.”

“Have you spoken to the landlord?” I asked.

“Why, yes, just now, while I was making your appointment, Captain Hastings. They said they had had some enquiries about flats in Whitehaven Mansions, and after hearing about M Poirot’s death they had presumed that the flat would soon be back on the market and had shown some people round. I never met any of them, but then I have only been coming in for an hour or so each day to keep an eye on things.”

“That explains that,” then I said. “The letting agent brought the post in with him, including the letter by hand.”

“It does nothing of the kind,” Miss Lemon replied quietly. “This letter was typed on my own machine. Would the agent stand by and watch someone sit down at my desk and type a letter, a letter moreover to someone whom they knew was dead?”

I was beginning to realise the force of Miss Lemon’s cool application of logic. This was a formidable character. We had landed ourselves with something of a small mystery, but I felt sure, after only knowing her for an hour, that between us she and I would would get to the bottom of it.  I began thinking about the other letters she had mentioned that were asking for help and a little idea began to form in my mind …

“It’s getting dark”, said Miss Lemon. “I must be getting back to my home while the light lasts. What time do you want me to come in tomorrow?”

“10 o’clock, at Baxter Payne and Lepper,” I replied promptly. “It promises to be one of the more interesting lease renewals and I would like your eyes and ears there with me.”

Miss Lemon nodded. We walked out of Whitehaven Mansions and into Sandhurst Square. We said our farewells, and I made my way thoughtfully back to my hotel.