Sir Tim Berners-Lee explains why he pays for online services

Sir Tim Berners-Lee, the British computer scientist credited with inventing the worldwide web, has renewed his call for a digital Magna Carta.

It would be a written constitution to guarantee the rights of internet users, a nod to the medieval document that is a cornerstone of English constitutional history.

He made his call at the Web We Want, external festival, which launched at the Southbank Centre in London this weekend.

He talked to the BBC's Dougal Shaw about the impact on an individual's privacy when using free-to-use services like Facebook or Google.

And he explained why he is prepared to pay for online services in order to avoid his personal details being shared with third parties.