"We built a media business inside a company that isn't one." That's how Sam Eads describes Trainline Media, which reaches more than 27 million travellers. Trainline exists to get people where they're going. They book on its app and website, check it while they wait at the station and keep it open as they travel.

Sam joins us at Future of Media London to talk about how that works in practice: the case he had to make internally, where Trainline decided ads should never go, and why they measured attention independently from day one. Then we'll get into the wider question: Can every app with an audience becomes a media owner?