1.075.1 Bletchley Park, NMOC, Codebreakers, Euston panic

Saturday, 2/15/2020

I should mention that my run of surprisingly good weather continues. Yesterday rain was forecast for the afternoon, so I carried my umbrella, but never opened it. Today the forecast is for cloudy only, so I went out without the umbrella. Of course, I got rained on, but only a little.

My breakfast spot, Les Filles, didn’t open until 8, so I had breakfast in the hotel. Then off to Euston station via the Central and Northern lines. I’d not been in a British rail station in modern times. There’s a vast open hall with a gigantic reader board spelling out in detail which trains are departing when and from which platform, and exactly what stops they make. I took the 9:15 to Crewe whose 2nd stop was Bletchley. And off we go, as smooth and fast as the German trains I enjoyed a decade ago. The first half hour is through pretty dreary industrial suburbs. About the time open fields and trees appear, we are stopping at Bletchley.

Out of the station, it is not entirely clear where to go; there’s no signage to Bletchley Park or its two museums. But the maps app suggests turning right; and there just down the road is a modest sign for the Park. Inside, the pedestrian visitor hoofs it quite a ways before a small sign directs him to the visitor center for the Codebreakers museum. Persevering through the car park one finds another small sign that points up hill to the building that houses the National Museum of Computing (NMOC). I was a few minutes ahead of opening time but fortunately the door was open so I could shelter from the light rain while the staff got themselves together.

I shan’t write much about the NMOC at this point. I was very interested, saw several neat things, and took pictures and videos. But I want to put those all together in some coherent sequence, either as a separate blog post, or as a slide show, so that I can talk to my fellow CHM people about the NMOC and my impressions of what it does well and poorly compared to us.

I had a fairly pathetic sandwich in the NMOC’s shop/snack bar, then went down to the Codebreakers exhibit. This separate museum tells the story of all the people who worked on the process of gathering intelligence from German radio transmissions.

There were many parts to the process. There were separate listening stations with directional antennas up and down the British Isles and they tried to triangulate so as to know the exact source of a transmission: was it in the North Atlantic? Was it moving? and so on.

The transmissions were recorded; they were frequency-shift keyed audio, bleepity bleep. This was rendered visually by a pen on a strip of paper showing the high and low tones. It was explained to me that it was a five-bit code, plus a low start bit and a high stop bit, so seven bits to a character. The wiggly line on tape was transcribed by eye to characters. That is, operators read the wiggles on tape, mentally picked out the character patterns, and hit keystrokes to transcribe them as holes in punched paper tape. Of course the transcribed characters were a random sequence; the messages were enigma-encoded strings. For that reason, each transmission was transcribed twice, then the punched tapes were visually compared to find mismatches, which would be transcription errors that would mess up the decryption process.

The transcribed punched tapes were given to motorcycle couriers (who were often women, WRENs) to drive to Bletchley. There the decoding process began. At first decryption was manual. Later it was done using the “Bomb”, an electro-mechanical device, and later still the Colossus, the kinda-sorta digital computer based on Alan Turing’s work, but actually implemented by engineers from British Telecom.

After decoding, the transmissions had to be translated by people who understood German military vocabulary and special terms, and then interpreted by intelligence people and delivered to decision-makers.

The Codebreakers is a pretty thin exhibit; it has display cases with artifacts of the workers, including their working papers and books; and interpretive panels. However other than a courier’s BSA motorcycle, it has no hardware to show. All the decoding stuff, the Bomb and the Colossus, are up the road at the NMOC. I was in and out in a half-hour, and I wouldn’t recommend it to anyone else.

So, back to the Bletchely station and was happy to learn a Euston-bound train was due in 15 minutes. The train up had been nearly empty, but southbound in the afternoon it was nearly full.

At Euston rail station I was out the door, around the corner, and into Euston underground station, and as I neared the top of the down escalator a very strange scene was taking place. There were two escalators going down, as usual with a solid line of down-going people on each, but as I walked up to the head, there was shouting, some kind of disturbance ahead, and… there were people climbing up the down escalator, pushing past the people standing going down. Lots of people were coming up, which is quite an effort; those escalators are not slow.

My first thought was, it’s a few kids having a bet. But no, they were mature people and they weren’t laughing. Slowly it dawns on me and the other people who are backing up into a mob at the head of the escalator, that they are running away from something down below on the platforms.

London Transit people responded with admirable promptness. Both escalators were stopped immediately. Transit people in orange vests started saying, back up please, we have a situation, leave the station. I heard someone near me say, “there’s a suitcase”, which I took to mean, an abandoned one that looked suspicious. I have no idea if that was the case. Realizing I had nothing to contribute or to learn, I turned around and exited the station.

(Four hours later the Manchester Guardian reported: British Transport Police said “Officers were called to Euston station at 1:27pm following reports of an altercation between two men involving the use of a knife. Our investigation found that there was no knife involved and no stabbing took place. The incident has been classed as ABH assault.” It must have been a pretty violent altercation to cause at least a dozen people to climb up the down escalator to escape it. But whatever; life in the big city.)

Out on the street, in light rain; how to get home? Euston is a bus transit center, and I asked at the bus kiosk if there was a bus that would take me near Lancaster Gate. No, I’d have to use two buses. Pfft, I’m too good for that, I’ll take a cab or an Uber. However, there are police sirens in all directions (and I have to say, modern emergency vehicles have ordinary sirens, no more klaxon hee-haw noises) and pretty clearly traffic will be jammed around here, and cabs hard to find. So I walked a few streets away. No cabs in sight so I called an Uber, which took a while to come, but was driven by a jolly Jamaican man, and the ride took me through parts of London I hadn’t seen. Regent’s Canal, with narrow boats parked along it, for one.



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