From early 2016, his concerns about the company’s business model, culture and priorities became ever graver, leading to a crusading new role that turned him from fervent champion to fierce critic. In the years since, as tech-driven scandal and crisis has hit countries from the US to the UK, from Sri Lanka to Brazil, McNamee has become a leading light in the fight against the existential threats posed by Facebook and the big tech giants to our privacy, democracy and public health.