Why Every Classic Companion Left Doctor Who

It's ironic that Jamie's arrival spelled the end for Ben Jackson, given that actor Frazer Hines had unsuccessfully auditioned for the role a few months before joining Doctor Who in Patrick Troughton's second serial, The Highlanders. Jamie was originally intended as a one-off character, but he made such an impression that the production team decided to keep him on.

Hines would remain on Doctor Who throughout the Troughton era, and the role made him a household name. Hoping to capitalise on this, his agent tried to persuade Frazer to leave Doctor Who while the going was good, mid-way through his third season. 

However, he was convinced to see the season through by Patrick Troughton, and they left together at the end of The War Games.