Conway in Cambridge
The Atlas of Finite Groups was published while Conway was still in Cambridge. Before then, it consisted of a huge scrap book that lived on a table in the DPMMS (Pure Maths) common room, containing the character tables of the groups.
I knew him well when I was a student in Cambridge from 1979 to 1986.
Conway's lectures were always lively, popular and full of insight.
But it was next to impossible to take notes from them. I remember attending one in a room with two parallel sets of blackboards that moved up and down on pulleys: he drew diagrams on one, with arrows across to the other one, and then moved the boards around.
In those days there were SIX student maths societies in Cambridge (the University one and five "college" societies, three of which have since folded). Every year the secretaries would fight for who got Conway to give a lecture to their society.
Although I did my PhD in category theory,
For Part III (equivalent to MSc) I was the only student who took the exam for Conway's course, which was about sphere packing, leading up to the 24D Leech Lattice and the monster group.
While I was a PhD student after that, I would be sitting minding my own business in the Pure Maths common room and Conway would come and sit beside me to describe his most recent construction of the Monster Group.