Sky has added 'green button' functionality to its service, allowing people to watch more of the adverts that appeal to them.

Although the red button has become a common phenomenon, Sky is now co-opting another of the coloured buttons to its cause, offering a bookable advertising service.

So what does this actually mean? Well, for anyone who sees an advert that they like, pressing green will now offer things like extended advert versions, more information and exclusive content.

Series link?

Sky's bookable service can run from a few minutes to hours and, believe it or not, can even be series linked.

With PVRs piling the pressure on advertisers, it's a tough time, but Sky appears to be hoping that, with greater interactivity, adverts can become a more viable sales mechanism.

Of course, if the adverts are as dull as most of them, the chances of you actually using the service are low – but that's neither the consumer nor Sky's problem.