Silicon Brits: The email killer

Few start-ups are causing as much buzz as Slack.

The collaboration tool provides workmates with a way to avoid having to wade through emails sent from each other.

It has been valued at $3.8bn (£2.9bn), thanks to its surge in popularity as the tool-of-choice for colleagues working together in thousands of companies around the world.

Cal Henderson, Slack's co-founder, is British, as are many of his team.

But he doesn't think Slack could have been a success in Britain.

He spoke to the BBC's North America technology reporter, Dave Lee.