When fish rain from the sky above Ealing, Sarah Jane and her friends are drawn to a recently-unearthed totem pole which is being displayed at a local museum. Clyde messes about with the exhibit, and winds up with a livid splinter. He thinks nothing of it until the next day, when everyone suddenly turns against him: Sarah Jane orders him out of her house, Rani says she hates him, and even his mum wants nothing to do with him. Only Sky is immune but, while she tries to get to the bottom of the strange sequence of events, Clyde is left to eke out a life for himself on the streets of London with the help of his new friend, Ellie.

In February 2009, Phil Ford, the lead writer for The Sarah Jane Adventures, was a guest at the Gallifrey One: 20 To Life convention in Los Angeles. He took the opportunity to meet with executive producer Russell T Davies, who had recently relocated to California. During lunch, they conceived a story idea which would place the spotlight firmly on Clyde Langer, since both men agreed that actor Daniel Anthony deserved the opportunity to tackle a more mature, complex narrative. Davies suggested the mystical means by which Clyde would find himself living on the streets of London, and Ford then developed these concepts into The Curse Of Clyde Langer. It would become Ford's second contribution to the fifth season of The Sarah Jane Adventures, following immediately after the year's initial serial, Sky.

Director Ashley Way was assigned to both Sky and The Curse Of Clyde Langer, which formed the fourth recording block for the 2010 and 2011 episodes. The Clyde-focussed narrative provided the opportunity to bring back two actors who had not been seen since the second season in 2008: Jocelyn Jee Esien as Clyde's mother, Carla, and Elijah Baker as his schoolmate, Steve Wallace. It was then decided that an additional scene involving Carla would be filmed for 2010's The Empty Planet. Cast as Dr Maddigan was Sara Houghton, who had previously appeared in programmes such as Trust and Holby City. Houghton's father, Don Houghton, had written the Doctor Who stories Inferno (1970) and The Mind Of Evil (1971), while her mother, Pik Sen Lim, had appeared in the latter as Captain Chin Lee.

The first three days of recording on The Curse Of Clyde Langer spanned June 22nd to 24th, 2010, and were spent on the attic set at the show's usual production home in Upper Boat. On the 25th, Ebeneser Chapel in Cardiff served as the Steven's Point soup kitchen; some filming also took place on nearby Charles Street. Work on June 28th dealt with the scenes of Clyde being chased by his schoolmates, beginning at Grange Gardens in Cardiff, and continuing to an alley off Llanmaes Street, then Hope Street, School Street and finally the premises of PI Underwood and Son, which also provided the area under the railway arches. The 29th was another busy day in Cardiff, starting with material outside the Museum of Culture, which was actually the Old Library. Cast and crew then moved to St John's Church, outside of which Clyde tried to use the automated teller, and where he and Ellie later panhandled. Finally, Ellie found Clyde on Crockherbtown Lane.

The interior of the Museum of Culture was actually the Coal Exchange in Cardiff, where recording took place on June 30th. On July 1st, a house on St Asaph Close in Cardiff posed as the Langer residence; this was a different venue than the one which had been used in The Mark Of The Berserker. Work there concluded on the 2nd, after which Way's team moved to Cardiff High School for scenes at Park Vale Comprehensive. A sequence in Sarah Jane's living room was filmed at Clinton Road in Penarth on July 7th, and a variety of inserts were taped at Upper Boat on the 11th. July 12th was another day spent at multiple Cardiff locations. The area where the homeless people were living rough was Taffs Mead Embankment, after which various scenes were recorded on Charles Street, most notably Clyde learning of Ellie's departure. More Bannerman Road material was taped at Clinton Road on July 20th, leaving just some pick-up shots to be completed the next day on Hadfield Road in Cardiff.

Post-production altered Clyde's opening narration, incorporating a new line which made reference to Sky, who had just been introduced in the preceding story. A significant edit involved the sequence of Clyde and Ellie panhandling in Episode Two. In the excised material, Rani emerged from the nearby supermarket and tossed Ellie some coins without taking note of her companion. She and Haresh then drove off while Clyde told Ellie that Rani was no longer somebody he knew.

• Doctor Who Magazine Special Edition #32, Autumn 2012, “Episodes 5.3/5.4: The Curse Of Clyde Langer” by Andrew Pixley, Panini UK Ltd.