Snow serves as President of the Council for British Archaeology and is a member of the Royal Historical Society. As an atheist and a humanist, he is a Patron of Humanists UK and an Honorary Associate of the National Secular Society. He is also an advocate for political reform, being the Electoral Reform Society's first ambassador. He played a prominent part in the 2011 Alternative Vote referendum in the UK; after he released a successful viral video, the campaign used a version of it, featuring him, as their final Referendum Broadcast.