Haydn has been a Research Associate and Academic Project Manager at the University of Cambridge's Centre for the Study of Existential Risk for the past six years. In that time the Centre tripled in size, and he advised the UK, US, and Singaporean governments; the EU, UN and OECD; and leading technology companies. He has over 40 publications with over 1,300 citations, including on climate change, pandemics, and societal collapse, but most of his work is on the security implications of artificial intelligence (AI). He is co-Chair of the Global Politics of AI Project and a Research Fellow at the international Leverhulme Centre for the Future of Intelligence.

Previously he worked in UK politics as the Senior Parliamentary Researcher to a Labour MP in the Shadow Cabinet, and was seconded to several general election and referendum campaigns. He was a Policy Associate at the Global Priorities Project (University of Oxford) and the first Development Director of the Centre for Effective Altruism.

He is a DPhil/PhD Candidate in International Relations, and has an MSc in Politics Research and a BA in Politics, Philosophy and Economics (PPE), all from the University of Oxford. His thesis 'Bombs, Bugs, Bytes and Bots' is on the history and future of arms control - what lessons from the varied success of arms control regimes for nuclear, biological and cyber weapons can be applied to international governance of artificial intelligence?