I was a graduate student of Doug's in the late 1990s. (In fact I was the only grad student in my cohort, so some grad `seminars' with Doug were one-on-one.) I remember Will Thompson, another grad student at the time, mentioning Doug's unique way of holding such a seminar: give a problem that no one had ever been able to solve and we would work on it together, which was great fun.
While a grad student, I was working off-campus part time in order to support our family and when the summer of 2000 rolled along, I told Doug that I needed to go back to my other job full-time. I remember Doug saying to me "look, you're so close to finishing, let's meet in my office every second Tuesday evening and we'll aim to get you ready to defend by February."
So we did that, and those Tuesday night meetings were always something to look forward to.
It was thanks to Doug that I was able to finish the programme and also thanks in part to some very encouraging meetings with Doug, years later, in the mid-2010s, that I was finally able to fully get back into the academic world again.
Being mostly out of town, I haven't seen Doug for a few years now but have very fond memories of our past conversations.