Picocon
Picocon is the name given to a series of British science fiction conventions run by the Imperial College Science Fiction and Fantasy Society. Taking place on a Saturday, in February or early March in Imperial College's Blackett Building since 1984.
T-shirts and other merchandise related to the convention are typically emblazoned with the Greek letters ΨΦ, which can be read as Sci-Fi. Roles in organising the convention include the Sofa and the Beanbag.
The reason for the event numbering of the first conventions is unclear. One suggestion is that there was a predecessor Picocon event watching videos and playing board games, and that the first formal event with a guest speaker is therefore Picocon 2.