In preparation for Christmas and the premiere of this year's remaining Doctor Who specials, the BBC's official Doctor Who website launched their online advent calendar for 2009 earlier this month. The advent calendar will feature many exclusive treats over the next seven days and door number eighteen on the calendar is now available to open due to the fact that today is the eighteenth of December. Behind today's door, there's an exclusive extract from a new radio interview with both David Tennant and Russell T Davies. You can listen to this new audio clip here and content from behind the calendar's previous doors can be found here. This year's nineteenth door on the calendar will be available to open sometime tomorrow afternoon and details regarding the next special advent treat will be posted on this site soon. What do you think of this interview extract?