His work includes Bodies, Gentlemen's Relish, Robin Hood, The Vice and numerous episodes of Doctor Who.

He made his feature film directorial debut with The Flying Scotsman (2006),[1] which was the gala premiere at the Edinburgh Festival in 2006 and was consequently picked up for worldwide distribution by MGM.

He then went on to direct a one-off episode of Sherlock, "The Abominable Bride", which won the Primetime Emmy Award for Outstanding Television Movie, for the BBC in 2016.

Mackinnon was the lead Director and Executive Producer on Knightfall, a major new drama series for the History Channel/A&E Network, between 2016 and 2017.

In 2017 Douglas was a director and executive producer of an adaption of Good Omens by Neil Gaiman and Terry Pratchett.