One of the reasons I wrote *Alan Turing’s Manchester* was to make sense of the paradoxical way I heard Mancunians both take pride in the city’s role in Turing’s life and simultaneously condemn what happened to him when he was here. I attempted to sum this up in my final chapter, about the way in which Turing was cold-shouldered in the University’s computer department and forgotten and then reclaimed by its institutional memory. It’s the chapter of the book I am least happy with, but because because of that I’m going to post it here and see if it provokes any response. I’m planning to give a version of this at a seminar in the University on 7th November.

*I’ve removed the source references here but they can be found in the book itself. It assumes that you know that Max Newman and Patrick Blackett had together created a Calculating Laboratory to make and use electronic computer in Manchester, and Freddie Williams and Tom Kilburn, were recruited to that laboratory as, later, was Alan Turing. *

There are today two separate blue plaques on the same building complex off the Oxford Road, but you can’t see them both at the same time. There is one facing north shared by Williams and Kilburn, and after you take an inconvenient diversion around the Manchester Museum, there is one facing south for Turing, in a physical representation of a difference in viewpoint that has rumbled on ever since the events of 1948. Neither plaque says anything untrue but then again neither plaque mentions the other. They represent a history that portrays Kilburn and Williams as one type of thinker and Turing as another.

For most of the twentieth century, the history of Manchester computing simply started in 1948. ** **This said that Williams and Kilburn had been interested in the engineering challenge of making, rather than programming, a computer and that, it went, is what they succeeded in doing: *‘Freddie Williams was not, I think, interested in the computer as a computer. What we were interested in doing was creating the computer for other people to use*’. In this account Newman’s computing project had been an unsuccessful rival to Williams’, an account helped by Newman’s own lack of credit-seeking behaviour. ** **When a historical Turing re-emerged after 1983, it was as a National Treasure residing at Manchester at the time but with no relation to the machine, except through using it for his impenetrable biological mathematics. In 1998 the Department of Computer Science held a 50th anniversary celebration to mark the first running of the Baby: Turing, it’s said, was not mentioned on the day, and in 2006 one leading local computer scientist said *‘Colossus was not a machine in the direct line leading to the modern computer’*. This engineer’s history can’t be said to be wrong, but it is partial.

It wasn’t until the twenty-first century that the pre-Mark I history of the Manchester computers was quarried by revisionists aiming to re-establish the role of the mathematicians. They pointed out that, even years after the event, Williams had always been generous in acknowledging the mathematicians’ influence and had no difficulty recalling that *Tom Kilburn and I knew nothing about computers…Professor Newman and Mr AM Turing knew a lot about computers. They took us by the hand and explained how numbers could live in houses with addresses*. In 1948, it was as electronic engineers, not as computer architects, that Williams and Kilburn led the world. ** **Kilburn, by contrast, was much more grudging: *‘Between 1945 and 1947 somehow or other I knew what a digital computer was…where I got that knowledge from I’ve no idea’*. In fact he had got it from attending a series of lectures: the lectures given by Turing. It’s unlikely that Kilburn in these later comments was deliberately obscuring credit due to Turing, and more plausible that he just didn’t remember owing anything to the mathematicians. As a young PhD student Kilburn was not interested in the past, and quite insulated from the administrative background. There is no patent on an idea, or on a funding decision, and rightly it was Kilburn listed as inventor on the computer memory patents, not Turing or Newman or Blackett.

The final glimpse we have of Kilburn and Turing working together is over a long summer night in June 1950. After the somewhat fake demonstration for the BBC of doing Mersenne mathematics on the Manchester Mark I there had been a year of work by Turing on an actual research problem. Turing had developed code to explore a pure mathematical axiom known as the Riemann Hypothesis, and that, together with some work on an optical problem, may have been all that the machine did for a year. Finally, in June 1950, the Riemann code ran successfully, all night: *‘The calculations had been planned some time in advance but had in fact to be carried out in great haste. If it had not been for the fact that the computer remained in serviceable condition for an unusually long period from 3 p.m. one afternoon to 8 a.m. the following morning it is probable that the calculations would never have been done at all’*. ** **An engineer had to be on standby whenever the machine ran and it was Kilburn who stayed overnight with Turing and ensured the unusually long uptime. This was the first application of the Manchester computer to generate a mathematical paper, but it was also the time at which Kilburn began to realise that the aims of the Manchester logicians and (perhaps unknown to him) cryptographers were very different to those of the applied mathematicians using computing resource elsewhere in the world. Henceforth, he said, he would address the latter, and in doing this he chose a group of consumers with practical, well-funded, and plausible needs who would in fact drive the economic development of the computer for decades. It meant that Manchester computers would be used to do the large repetitive calculations needed by the atom bomb projects. This was the opposite use to the automated reasoning that Newman and Blackett had intended. Newman seems to have accepted this, though it took Manchester off a path pointing to intelligent machines. Blackett, on the other hand, was unhappy, perhaps because of his opposition to atomic weapons themselves.

But Blackett no longer had any leverage over the project. Though Kilburn and Turing worked together in the early days, they never collaborated in any intellectually meaningful way. Had they done so, the potential for an early breakthrough in artificial intelligence would have been enormous. They were two people of creativity and achievement, with much knowledge and background in common, and with different and complementary skills in a field ripe for innovation. But something about those differences kept them apart. They were both productive bees, but one looked like an ant and one a spider. This is a story where it is very tempting to align two men on opposite sides of an apparently intuitive divide. Asked to assign one member of each pair from: North/ South, Manchester/Cambridge, grammar school/public school, engineer/mathematician, applied/pure, doer/thinker, hardware/software, trade/gentry, earned/ entitled, patent holder/private thinker, the labels that apply to Kilburn/Turing might seem at first obvious and factual. Binary reductions are as addictive as they are misleading, so that adding into the list masculine/effeminate, straight/gay, legal/illegal might give hardly more pause for thought. It is a short step, then, to a conclusion that manly Manchester’s judgement of Turing as an effeminate Cambridge criminal led to ostracism and Turing’s depression and suicide. But it is a simplistic step without direct evidence. There is clear evidence that there was coldness. Perhaps it was the engineers that felt looked down on: some of the mathematicians considered Williams and Kilburn as not *‘ideas men’*. ** **Williams later gave a lecture, *Engineering Must Not Degenerate Into Mathematics, *which under cover of a successfully jocular tone revealed a distinct bitterness about the class distinctions in the *‘traditional aristocratic attitude: to be really tops two things are required: (a) one must be supremely good at something. (b) The something at which one is supremely good must be absolutely useless’*. ** **It was more than class, though. Kilburn and Turing are recorded by multiple sources as not getting on, and Geoff Tootill, in long hindsight, speculated that this was because Kilburn knew of Turing’s sexuality. But after this the binaries start to fray. Tootill also thought there may have been disapproval of Turing’s general untidiness and tendency for his underpants to show above his trousers, and another programmer thought Kilburn in general liberal and broadminded. ** **The dichotomies don’t always survive inspection: Kilburn had had a Cambridge mathematics education too, and Turing also came to Manchester through choice and with hands-on electronic expertise. And though to begin with Turing was paid more than Kilburn, by 1954 Kilburn’s career prospects and consulting fees were rapidly improving. There may have been a ‘jagged rift’ between the engineers and the mathematicians, but it was perhaps more a silence of incomprehension than anything more destructive.