The popularity of Dr.Who has been varied in the age-groups it's been a hit with, not just for children as not initially expected (though probably the main aim aside from family viewing in the early evening of Saturday) but in those that grew old but didn't quite grow-up. On from the initial show, there has been the announcement of something described as more adult, the spin-off 'Torchwood'. Then there was the revelation that early plans had been scrapped for a spin-off based entirely around Rose Tyler, the Doctors' assistant for the first two new series, which was deemed to go beyond the boundaries of how the show works well in terms of the change-around of characters.
Now there's a connection to the past of the Doctor being made with the appearance of a new spin-off show announcement, for a show based around John Pertwee's assitant (well, one of them, I am too young to remember) - we have the childrens drama 'The Sarah Jane Adventures', due to begin with an hour-long special in the new year and continue (I predict September next year, when the new late-year season starts) with a series at a later date in 2007.
Childrens TV, particularly on the BBC (shown as two-hour segments in the early afternoon, as well as recently becoming one of the additional dedicated channels), has a long history of expensive and substantial (and relatively challenging) dramas that appear with regularity. In recent years they haven't been so obvious and the budgets haven't been quite what they once were, but Doctor Who has already made some transfer into this part of the demographic with a fan show which presents behind-the-scenes footage, guest interviews, quizes and so on - an encouragement to all the fan activity within the younger age groups. In the past these shows have had some family appeal too, often repeating on early Sunday Evening slots, cut into movies or show in omnibuses.
Although this might mean we have three Doctor Who connected shows with three relatively distinct age groups being aimed at, I wouldn't put it past the BBC to make more examples of such shows - perhaps an animated series? - or to chop and change them in a way which is acceptable, perhaps changing the focus of a show that surrounds one ex-assitant to focus on another... they seem to both want this to run and run, and also to potentially use it as a rather fickle exploitation of its' past successes. Cue the 'Robin Hood' revival, for example; well-trodden ground, but also never guaranteed successful. [Source : Official Doctor Who].