The thought has struck me that since Doctor Who came back on our screens two years ago, each season has seen the return of some classic foes. Daleks in Season One, Cybermen in Season Two, and The Master in Season Three, plus more minor foes in Rose and Gridlock.
Admittedly there are some rumours that this guy will make a return in Season Four, but I think it would be good to see a recurring ally of the Doctor, esp as we have already seen some former companions briefly return in Seasons Two and Three.
Thing is there was only one major recurring ally in Doctor Who and that was Brigadier Lethbridge-Stewart. For those who don't know he headed UNIT in the UK and was perhaps the Captain Jack Harkness of the early 1970s, or possibly not : ?