It was the letter in which he offered me the editorship of Medical Hypotheses.
This was posted on my Miscellany blog last year - but I am copying it here for the record.
Although I am slowly recovering from the latest recurrence of my mantle cell lymphoma, I have to be realistic and accept the probability that I have only a year or so to live. Rather than leave everything to the last minute, I would rather put things in order now.
[Note: in fact David had less time than he hoped, and he died just a few weeks later on 1 April 2003. We had a chance to speak a couple more times on the telephone - once while he was actually having chemotherapy - but that was all.]
I am therefore writing to ask whether you would be willing to take over as Editor-in-Chief of Medical Hypotheses? Frankly you are the only person I really trust to take it over and run it in an open-minded fashion.
The primary criteria for acceptance are very different from the usual journals. In essence what I look for are answers to two questions only: Is there some biological plausibility to what the author is saying? Is the paper readable? We are NOT looking at whether or not the paper is true but merely at whether it is interesting.
I now make most of the editorial judgments myself unless I am really puzzled as to whether the paper is a lot of nonsense. I have found most referees far more trouble than they are worth: they are so used to standard refereeing which is usually aimed at trying to determine whether or not a paper is true that they are incapable of suspending judgment and end up being inappropriately hypercritical.
In the early days I used to spend a lot of time editing and rewriting papers which were poorly written or where the English was inadequate. However, I am now quite ruthless about not doing that which has greatly reduced the editorial burden. I simply return papers which are poorly written, suggesting that they are rewritten in conjunction with someone whose native language is English. If that does not produce a result then the paper is simply rejected.
I do very much hope that you will be willing to take up this proposal. Overall Medical Hypotheses is a lot of fun and it gives one access to a very wide range of interesting medical science. Since I started the journal in Newcastle in the 1970s there is an appropriateness in the possibility of it returning there.
Very best wishes, David Horrobin.