When radio stations started playing music the record companies started suing radio stations. They thought now that people could listen to music for free, who would want to buy a record in a record shop? But I think we all agree that radio stations are good stuff.

As an investor, what we're not looking for is 'oh this is a cool app,' it's 'is this something that can become a big business?' You need to find those that can become real businesses.

When we look at investing, we always think about 'how defensible is this, how likely is it that somebody is going to copy this.' E-commerce tends to be something easy to copy because it's execution.

Look for when the environment is changing - the big shift now is mobile Internet. It's really happening big-time. The way you interact with services on a smart phone compared to the Web is quite different, so there's a huge opportunity.

Skype is easy enough to use so that people don't need to be tech savvy - a lot of users just want to communicate with their friends and family, and they find this is the easiest, cheapest way.

And the VCR did the same thing: the movie industry thought nobody would ever watch movies any more.

The telephone is a 100-year-old technology. It's time for a change. Charging for phone calls is something you did last century.