It is a standard part of our job and our responsibilities to write letters of reference for students and postdocs, past and present. But I sometimes get very frustrated by those who ask me to write a letter of support for them, when they are not not just from my past, but from my very deep past. No doubt the person who makes the request believes that their case will be strengthened by having me as a referee simply by virtue of the letters after my name. But I would beg to differ. If it is a decade or two since they worked with me, during which there has been zero contact, I cannot believe that anything I write will look convincing. Even if supplied with an up-to-date CV, how can I write a strong letter of support if all I can do is reiterate stuff that is already clear from that document and to which I cannot add chapter and verse? I am never overwhelmed by bland letters of reference myself – ‘Dr X worked with me between A and B and was a conscientious researcher with whom I wrote two papers’ is the sort of thing I have in mind that is pretty much useless – and I see no reason to believe anyone else would be either.
If it is someone who has kept in touch with me, who has been briefing me on what they have been getting up to since they left my group or sending me preprints sharing their progress, then it is a different matter. There are plenty of past group members who fit into that category. But if it is someone who left literally twenty years ago and vanished from then until the begging email arrives, no I won’t do it. By and large I try to set a limit of around 10 years maximum for past group members whose contact since they left has been limited. If I don’t know how well their subsequent research and career has been going, it’s not so much that there is a gap in years since they were a keen young PhD student with me, more that that gap means the person I describe from my own personal knowledge will have long since transformed into someone else with (one hopes) additional strengths about which I can know nothing. To say that fifteen or twenty years ago they were blushingly shy or an arrogant so-and-so will not (necessarily) have any bearing on the person they have become, let alone what battery of up-to-date techniques they now have under their belt.
Just occasionally I find it hard to conjure up the character in sufficient detail even to write a good description of what they were like when they were part of my group, certainly not enough to provide a meaningful, kind or useful character sketch. This post is of course prompted by a particular request, but it has caused me to think about some of those who worked with me whose character I can only recall in outline and not necessarily a helpful outline at that. There was the student who left a tap running overnight causing flooding of a stairwell; luckily nothing more significant was damaged. There was another who failed to show up for a meeting with their industrial supervisor due to a massive hangover. That one got a stern lecture on their duties in the professional sphere. I’m sure it didn’t stop them binge-drinking in the future, but never to the extent that they couldn’t make a meeting they were committed to the next day during the rest of their PhD. The foibles of this couple of students stand out clearly in my mind, but those aren’t comments I would wish to put in a reference letter.
There are others whose positive qualities still shine out in my mind, even more than a quarter of a century later: the ones who were amazingly good at the logistics of preparing samples in good time for a three day shift at the synchrotron, for instance, to be contrasted with the ones who left it all to the last minute. There were the ones who used to get incredibly nervous about having to give a talk in public, literally shaking, but who – when push came to shove – would deliver a brilliant presentation with great apparent aplomb (even if still shaking internally or even externally). They perhaps could also be contrasted, this time with the more confident but less able student whose preparation was limited and whose delivery was consequently equally limited. Some students stand out for good reasons, some stand out for bad and some, I’m afraid, just don’t stand out at all after too long an interval.
Dear reader, if you want to request a reference from a prior employer or supervisor you should think whether they can write anything useful. I reiterate, bland references won’t do your job prospects much good. Thorough, meaningful(sometimes humorous, sometimes vicious) references are still the norm in academia, unlike in many other professional spheres where little more than dates of attendance and sick record may be given. It really is necessary for the referee to have something current to go on, ideally something from first-hand knowledge. I want to be helpful, of course I do, but I also need to be honest. If there is little for me to go on that is up to date so that I end up writing something that is colourless, the person receiving the letter of reference will immediately smell a rat. A bunch of fancy letters after my name won’t cover up that fact and your CV will have shown that you passed through my group anyhow.