Clara wants to meet Robin Hood, but the Doctor scoffs at the notion of seeking out someone he believes to be a fictional character. No sooner do they land in 1190 Sherwood Forest, however, than they encounter the legendary rogue and his Merry Men. The Doctor and Clara learn that the countryside is indeed being oppressed by the Sheriff of Nottingham, who is stealing gold and kidnapping peasants for labour. But when the Sheriff's knights are revealed to be robots and his castle turns out to be a spaceship, the Doctor becomes more convinced than ever that Robin is not what he appears.

One of the themes that executive producer Steven Moffat wanted to explore during Doctor Who's thirty-fourth season was the extent of the Doctor's heroism. This would be made explicit in the second episode, Into The Dalek, with the Doctor asking Clara if he was “a good man”, leaving his companion unsure how to answer the question. To reinforce this quandary, Moffat wanted the next story to juxtapose the Doctor against a traditional hero of English folklore. A natural choice was Robin Hood, a champion of the poor and oppressed whose mythology dated to at least the fourteenth century; debate persists as to whether or not the character had any factual basis. In the legend's most common form, Robin Hood was a deposed nobleman who stole from the rich -- represented by the cruel Sheriff of Nottingham, who had come to power while King Richard the Lionheart was away waging the Third Crusade -- and gave to the poor. He lived in Sherwood Forest with his band of Merry Men, and courted Maid Marian.

To write the Robin Hood story, Moffat turned to Mark Gatiss, who had most recently contributed Season Thirty-Three's Cold War and The Crimson Horror. Gatiss had been tasked with “celebrity historical” scripts before, including 2005's The Unquiet Dead featuring writer Charles Dickens and 2010's Victory Of The Daleks which involved Prime Minister Winston Churchill. The notion of pairing the Doctor with a folkloric character, rather than a real historical figure, presented an interesting twist on the genre. In addition to Robin Hood, Moffat asked Gatiss to include a science-fiction element in the form of a robotic nemesis.

The Adventures Of Robin Hood (1938) suggested the very literal take on the Merry Men

Gatiss began working on his adventure around the summer of 2013. It quickly became known as Robot Of Sherwood in reference to Robin Of Sherwood, which had run for three seasons in the mid-Eighties with Michael Praed and then Jason Connery in the title role. Amongst all of the legend's many adaptations, Gatiss particularly drew upon The Adventures Of Robin Hood, the classic 1938 film version starring Errol Flynn. Amongst other elements, it suggested the very literal take on the Merry Men, whose demeanour would be unnaturally jovial and lighthearted.

In early drafts of Robot Of Sherwood, a key figure was the antlered Hunter. It was revealed to be the interface for the crashed spaceship; its head had been damaged and so it now wore a stag's skull to hide its disfigurement. The Hunter could control the Merry Men, and at one point they pursued Clara from their campsite so that she could be recaptured by the Sheriff. Amongst the Merry Men was Much the Miller -- whom tales usually denoted as the Miller's Son, and who was one of the oldest characters associated with Robin Hood. Quayle was female and lacked a ward, but Robin was shown to be in a romantic relationship with a man named Marian. The Sheriff was revealed to be a robot; he initially died by beheading, and later by falling into the spaceship's engines, before Gatiss decided that he would meet his fate in the pool of liquid gold. Briefly, another common trope of Robin Hood stories was incorporated by having King Richard return from the Crusades to reassert his authority at the narrative's conclusion.

Since a plot point of the adventure was the lush greenery of Sherwood Forest -- inspired by the Technicolor hues of The Adventures Of Robin Hood -- it was decided that Robot Of Sherwood would be amongst the third pair of stories to go before the cameras. This meant that it would be filmed in the spring of 2014, rather than during the winter months. Joined by episode six, The Caretaker, it would be directed by Paul Murphy, who was known to the BBC Wales team via his work on Casualty and Wizards Vs Aliens. Cast as Alan-a-Dale was Gatiss' husband, Ian Hallard, who had previously enjoyed a small role in the fiftieth-anniversary docu-drama An Adventure In Space And Time. Playing Robin Hood was Tom Riley, another friend of Gatiss', who was best known as the star of the fantasy series Da Vinci's Demons. Ironically, Riley received the offer to appear in Robot Of Sherwood as he sat in the audience at the Donmar Warehouse in Covent Garden, London... where Gatiss was appearing in a production of Coriolanus.

Filming for Block Three initially concentrated on The Caretaker. Nonetheless, amidst this work, the TARDIS sequences for Robot Of Sherwood were taped at Cardiff's Roath Lock Studios on March 25th and 26th. It would be almost two weeks before more recording took place on the Robin Hood adventure. On April 8th, the village where the Sheriff captured Maid Marian was actually Cosmeston Medieval Village near Penarth. This was a recreation of an authentic fourteenth-century settlement, which had been unearthed in the Eighties during the development of the Cosmeston Lakes Country Park.

Principal photography for Robot Of Sherwood finally began on April 14th and 15th at Fforest Fawr in Taff's Well, with Murphy tackling scenes outside Nottingham Castle and at the Merry Men's encampment. From the 16th to the 18th, Caerphilly Castle in Caerphilly posed as various parts of Nottingham Castle. It provided the Sheriff's quarters and the moat on the first day; the courtyard where the archery tournament took place on the middle day; and the area outside the bridge, the dungeon, the moat, and various inserts on the last day. On April 19th, cameras rolled on the set for the spaceship bridge at Roath Lock. The following day was Easter Sunday, and cast and crew were given a week off.

As a result, production on Robot Of Sherwood didn't resume until April 28th. This was the first of four consecutive days at Roath Lock dedicated to sequences in Nottingham Castle which had not been recorded on location, including a number of pick-up shots. The 28th saw the completion of material on the bridge, followed by Robin and the Sheriff's duel on the beam and the start of work in the vault. The latter remained Murphy's focus through to May 1st. On May 2nd and 3rd, the glade where the TARDIS materialised was actually Pont Melin-fach near Ystradfellte. For the Doctor's duel with Robin, a special prop spoon was fabricated which would protect Peter Capaldi's hand. On the second day, Murphy also captured an insert of Robin firing the golden arrow after the retreating spaceship. Subsequently, additional TARDIS material was written for the end of the episode. It was recorded on June 10th at Roath Lock, with Murphy completing more pick-ups there on the 11th.

The databank sequence included a photograph of actor Patrick Troughton from 1953's Robin Hood

The establishing shots of Nottingham Castle were created in post-production, and were based upon Bodiam Castle at Bodiam, East Sussex -- the same venue which had appeared in 1983's The King's Demons. Another callback to Doctor Who's past came in the databank sequence which displayed various artists' interpretations of Robin Hood. Included amongst them was a photograph of actor Patrick Troughton from 1953's Robin Hood, the first television adaptation of the lore. The title role in the six-episode serial was just a small part of Troughton's extensive resume, which would later include the Second Doctor.

Robot Of Sherwood was scheduled for broadcast on September 6th. In the weeks leading up to the airdate, however, the world was rocked by the decapitation of journalists James Foley and Steven Sotloff at the hands of the Islamic State terrorist organisation. With Sotloff's death announced on September 3rd, executive producer Brian Minchin flagged Robot Of Sherwood as having potentially problematic content. This related to the events immediately prior to the climactic duel between Robin and the Sheriff, which would have seen the Doctor use a tapestry in the vault to incapacitate the Sheriff, allowing Robin to behead him. However, the villain was not dead because he was now a cybernetic lifeform, having been rebuilt by the robots after their spaceship crashed directly on him. The Sheriff's body threatened Clara, prompting Robin to rescue her by restoring the man's head. The pair then proceeded to their duel on the beam.

The BBC agreed with Minchin's concerns, and authorised a last-minute re-edit of Robot Of Sherwood. The loss of the beheading meant that the episode was abbreviated by about sixty seconds. Evidence of the omission remained in the sudden disappearance of the tapestry from the vault wall, and the Sheriff's description of himself as “the first of a new breed -- half man, half engine”. This shortened version of Robot Of Sherwood aired as planned on the 6th. With The National Lottery: Break The Safe having reached its second-season finale a week earlier, Doctor Who was now followed by The National Lottery: In It To Win It.

• The Doctor Who Companion -- The Twelfth Doctor: Volume One, June 2019, “Robot Of Sherwood” by Andrew Pixley, Panini UK Ltd.
• Doctor Who: The Complete History #77, 2016, “Story 244: Robot Of Sherwood”, edited by Mark Wright, Hachette Partworks Ltd.