Thanks for the post! Minor quibble, but it bothers me that "people" in the title is taken to mean "British adults". I would guess that the dietary choices of Brits aren't super indicative of the dietary choices of people in general, and since the Forum isn't a British platform, I don't think Brits are the default reference class for "people".
Military/weapons technologies, in particular nuclear weapons, biological weapons, chemical weapons, and cyberattacks
Several infectious diseases, including COVID-19, Ebola, SARS, MERS, swine flu, HIV/AIDS, etc.
Gene-edited humans (see coverage of / responses to the twins modified by He Jiankui)
Some more examples of risks which were probably not extreme*, but which elicited strong policy responses:
*I'm not really sure how y... (read more)
The 2014 NIH moratorium on funding gain-of-function research (which was lifted in 2017)
The Asilomar Conference on Recombinant DNA, which Katja Grace has a report on: https://intelligence.org/2015/06/30/new-report-the-asilomar-conference-a-case-study-in-risk-mitigation/
If you want to draw useful lessons for successful risk governance from this research, it also seems pretty important to collect negative examples of the same reference class, i.e. conditions of extreme risk where policies were proposed but not enacted/enforced, or not proposed at all. E.g. (in the spirit of your example of the DoD's UFO detection program), I don't know of policy governing the risk from SETI-style attempts to contact intelligent aliens.
Are you interested only in public policies related to extreme risk, or examples from corporate governance as well? Corporate risk governance likely happens in a way that's meaningfully different from public policy, and might be relevant for applying this research to e.g. AI labs.
2 of us were there for ~6 days. From conversation with the local organizers, it seemed like a big bottleneck on group activity was organizer capacity, e.g. they didn't have the capacity to run an intro to EA fellowship. So we focused our time on trying to find additional organizers. We did this by helping collect emails at the activities fair and emailing hundreds of people on the mailing list about setting up 1:1 chats. Currently, it looks like these efforts were unsuccessful.