With David Tennant having taken his final journey as nation's favourite Time Lord, here are some more classic regeneration clips from the Doctor's previous incarnations. The 7th August 1987 saw Colin Baker's reign as the Doctor comes to end when the TARDIS, under attack from the Rani, is forced to crash land leaving the Doctor with fatal injuries. Watch more high quality videos on the new BBC Worldwide YouTube channel here: http://www.youtube.com/bbcworldwide