I thought I'd dig out some of Derek Martinus' work to watch and watched Galaxy 4 episode 3: Airlock, some of Tenth Planet 1 & 2, Evil of the Daleks 2 and Spearhead from Space. While doing this a few things struck me:
Derek Martinus seems to have been handed some of the more historically important directing jobs in Doctor: he handles the first appearance of the Cybermen, Ice Warriors, Autons and Third Doctor. He handles the famous Doctor & Companion free episode Dalek Masterplan, the prelude to the grand Dalek Masterplan. And he's on hand for the departure of William Hartnell and the intenmded final appearance of the Daleks. In all he directs 26 episodes which puts him fifth on the all time list of Who episodes directed. The four directors above him on the list are all recognisable names to Doctor Who fans.
| DIRECTOR | EPISODES | EXISTS | MISSING | EXISTS % | MISSING % | |
| 1 | Douglas Camfield | 52 | 38 | 14 | 73.08 | 26.93 |
| 2 | David Maloney | 45 | 45 | 0 | 100 | 0 |
| 3 | Christopher Barry | 43 | 33 | 10 | 76.75 | 23.26 |
| 4 | Michael Briant | 30 | 30 | 0 | 100 | 0 |
| 5 | Derek Martinus | 26 | 13 | 13 | 50 | 50 |
| 6 | Barry Letts | 24 | 24 | 0 | 100 | 0 |
| 7 | Pennant Roberts | 24 | 24 | 0 | 100 | 0 |
| 8 | Richard Martin | 22 | 22 | 0 | 100 | 0 |
| 9 | Michael Ferguson | 21 | 21 | 0 | 100 | 0 |
| 10 | Peter Moffatt | 20 | 20 | 0 | 100 | 0 |
| Ron Jones | 20 | 20 | 0 | 100 | 0 |
If we limit the episodes to the end of 1970's Season 7, the point where Martinus stopped working for Doctor Who, he'd directed the second most episodes behind, inevitably, the great Douglas Camfield:
| DIRECTOR | EPISODES | EXISTS | MISSING | EXISTSG% | MISSING% | |
| 1 | Douglas Camfield | 42 | 28 | 14 | 67 | 34 |
| 2 | Derek Martinus | 26 | 13 | 13 | 50 | 50 |
| 3 | Richard Martin | 22 | 22 | 0 | 100 | 0 |
| 4 | Christopher Barry | 20 | 10 | 10 | 50 | 50 |
| 5 | David Maloney | 19 | 19 | 0 | 100 | 0 |
| 6 | Michael Ferguson | 17 | 17 | 0 | 100 | 0 |
| 7 | Morris Barry | 13 | 11 | 2 | 85 | 16 |
| 8 | Hugh David | 10 | 0 | 10 | 0 | 100 |
| 9 | Mervyn Pinfield | 10 | 10 | 0 | 100 | 0 |
| 10 | Waris Hussein | 10 | 4 | 6 | 40 | 60 |
Of note in that list is relative newcomer David Maloney's 19 episodes, all in Troughton's last season.
But as you'll also see from that list over half of Martinus' 26 episodes are missing.
In terms of numbers of episodes missing he stands second behind Douglas Camfield who directed significantly more episodes during the period that episodes are missing from - 42 of Camfield's 52 episodes fall before the end of Season 7.
| DIRECTOR | EPISODES | EXISTS | MISSING | EXISTS % | MISSING % | Stories Missing |
| Douglas Camfield | 52 | 38 | 14 | 73.07 | 26.92 | Crusade Dalek Masterplan Web of Fear |
| Derek Martinus | 26 | 13 | 13 | 50 | 50 | Galaxy 4 Misison to the Unknown 10th Planet Evil of the Daleks Ice Warriors |
| Christopher Barry | 43 | 33 | 10 | 76.74 | 23.25 | Savages Power of the Daleks |
| Hugh David | 10 | 0 | 10 | 0 | 100 | Highlanders Fury from the Deep |
| Waris Hussein | 10 | 4 | 6 | 40 | 60 | Marco Polo |
| Julia Smith | 8 | 2 | 6 | 25 | 75 | Smugglers Underwater Menace |
| Gerald Blake | 12 | 7 | 5 | 58.33 | 41.66 | Abominable Snowmen |
| Michael Hart | 6 | 1 | 5 | 16.66 | 83.33 | Space Pirates |
| Paddy Russell | 18 | 14 | 4 | 77.77 | 22.22 | The Massacre |
| Gerry Mill | 6 | 2 | 4 | 33.33 | 66.66 | Faceless Ones |
| Tristan de Vere Cole | 6 | 2 | 4 | 33.33 | 66.66 | Wheel in Space |
| John Davies | 4 | 0 | 4 | 0 | 100 | The Macra Terror |
| Michael Leeston-Smith | 4 | 0 | 4 | 0 | 100 | The Myth Makers |
| Bill Sellars | 4 | 1 | 3 | 25 | 75 | The Celestial Toymaker |
| Morris Barry | 13 | 11 | 2 | 84.61 | 15.38 | The Moonbase |
| Henric Hirsch | 6 | 4 | 2 | 66.66 | 33.33 | Reign of Terror |
| John Crockett | 5 | 4 | 1 | 80 | 20 | Marco Polo |
Reordering the list by percentage reveals some surprises! 3 directors Hugh David, Michael Leeston-Smith and John Davies have their entire Doctor Who directing career wiped out by the episode junkings, but Hugh David is the only one of these to work on more than one story.
| DIRECTOR | EPISODES | EXISTS | MISSING | EXISTS % | MISSING % | Stories Missing |
| Hugh David | 10 | 0 | 10 | 0 | 100 | Highlanders Fury from the Deep |
| John Davies | 4 | 0 | 4 | 0 | 100 | The Macra Terror |
| Michael Leeston-Smith | 4 | 0 | 4 | 0 | 100 | The Myth Makers |
| Michael Hart | 6 | 1 | 5 | 16.66 | 83.33 | Space Pirates |
| Julia Smith | 8 | 2 | 6 | 25 | 75 | Smugglers Underwater Menace |
| Bill Sellars | 4 | 1 | 3 | 25 | 75 | The Celestial Toymaker |
| Gerry Mill | 6 | 2 | 4 | 33.33 | 66.66 | Faceless Ones |
| Tristan de Vere Cole | 6 | 2 | 4 | 33.33 | 66.66 | Wheel in Space |
| Waris Hussein | 10 | 4 | 6 | 40 | 60 | Marco Polo |
| Derek Martinus | 26 | 13 | 13 | 50 | 50 | Galaxy 4 Misison to the Unknown 10th Planet Evil of the Daleks Ice Warriors |
| Gerald Blake | 12 | 7 | 5 | 58.33 | 41.66 | Abominable Snowmen |
| Henric Hirsch | 6 | 4 | 2 | 66.66 | 33.33 | Reign of Terror |
| Douglas Camfield | 52 | 38 | 14 | 73.07 | 26.92 | Crusade Dalek Masterplan Web of Fear |
| Christopher Barry | 43 | 33 | 10 | 76.74 | 23.25 | Savages Power of the Daleks |
| Paddy Russell | 18 | 14 | 4 | 77.77 | 22.22 | The Massacre |
| John Crockett | 5 | 4 | 1 | 80 | 20 | Marco Polo |
| Morris Barry | 13 | 11 | 2 | 84.61 | 15.38 | The Moonbase |
Derek Martinus is the only Director with episodes missing from FIVE stories:
| STORY | EPISODES | EXISTS | MISSING | EXISTS | MISSING |
| Galaxy Four | 4 | 1 | 3 | 3 | 1, 2 & 4 |
| Mission to the Unknown | 1 | 0 | 1 | - | 1 |
| Tenth Planet | 4 | 3 | 1 | 1, 2 & 3 | 4 |
| The Evil of the Daleks | 7 | 1 | 6 | 2 | 1, 3, 4, 5, 6 & 7 |
| The Ice Warriors | 6 | 4 | 2 | 1, 4, 5 & 6 | 2 & 3 |
| Spearhead from Space | 4 | 4 | 0 | 1, 2, 3 & 4 | - |
| 26 | 13 | 13 |
In fact of the six stories he worked on only the last, Spearhead from Space is complete.
