Luke and Clyde's new classmate, Rani Chandra, has moved with her family into the Jacksons' former home on Bannerman Road. Sarah Jane is determined to prevent Rani from getting involved in her adventures, until she learns that the girl is being haunted by a malevolent clown. Clyde becomes convinced that the clown is connected to a spate of disappearances from their school. With Rani's help, they deduce that all of the missing children had a ticket to Elijah Spellman's circus museum. When they confront Spellman, he reveals that he is not only Odd Bob the Clown... but also the Pied Piper of old.

The first season of The Sarah Jane Adventures was an undisputed ratings success. It earned the digital channel CBBC some of its highest-ever viewing figures, while also garnering a substantial audience for its timeslot on BBC One. As such, it was with no small degree of confidence that, late in 2007, the production team began to plan for the future. It was agreed that the groundwork would be laid not only for a second season, to air in the autumn of 2008, but also a third season for autumn 2009. However, it quickly became clear that the continuation of The Sarah Jane Adventures would be accompanied by several changes, both behind and in front of the camera.

By now, producer Matthew Bouch had taken on additional responsibilities, including the producership of the BBC Three supernatural drama Being Human. Consequently, it was decided that a new producer for The Sarah Jane Adventures would be appointed, with Bouch retaining the more high-level role of series producer. This led to the addition of Nikki Smith to the production team; she been a script editor on various programmes, including the 2008 Doctor Who adventure The Sontaran Stratagem / The Poison Sky, and she had also been an assistant producer on New Street Law.

Phil Ford would take the role of lead writer on The Sarah Jane Adventures

Meanwhile, Phil Ford would now take the role of lead writer on The Sarah Jane Adventures, contributing half of the planned six serials for the season, and providing input on the other three; he would be credited as co-producer. Ford had originally been tasked with writing Eye Of The Gorgon for the programme's first season, after which he had assisted with the development of other scripts, such as Warriors Of Kudlak. He then wound up writing the season finale, The Lost Boy, when it was determined that executive producer Russell T Davies would have insufficient time to do so.

Finally, actress Yasmin Paige informed the production team that she would be unable to continue playing Maria Jackson. Paige would turn seventeen in 2008 and would be writing GCSE exams in the spring, when the putative second season would begin production. Respecting the importance of her education, Paige elected to temporarily step back from her acting career. It was decided that Paige would return to The Sarah Jane Adventures for the year's second recording block, in order to provide Maria with a suitable exit from the show; her parents, Alan and Chrissie, would also be written out.

However, this meant that a new young female protagonist was needed to fill the void left by Maria. To this end Davies developed Rani Rakhit, who would enter Sarah Jane's orbit due to her interest in becoming a journalist. To draw a clear distinction between the two teenaged girls, Davies opted for a very different family dynamic amongst the Rakhits than had been the case for the Jacksons: whereas Maria had been a child of divorce, Rani's parents would still be happily married. These characters were developed by Ford in concert with Gareth Roberts, who had scripted Revenge Of The Slitheen and Whatever Happened To Sarah Jane? for the first season, and who had co-written the introductory special Invasion Of The Bane. Rani's mother would be florist Sundra Rakhit, while her father would be Suresh Rakhit, whose new job as headmaster of Park Vale Comprehensive would provide additional opportunities to involve him in the lives of Rani, Luke and Clyde. The character names evolved over time, with Sundra becoming Gita, Suresh becoming Haresh, and the family name changed to Chandra.

Successfully auditioning to play Rani was Anjli Mohindra, who had appeared in Doctors and Coronation Street

After Sladen suggested that it was a fait accompli in an interview with SFX magazine published on January 25th, 2008, the renewal of The Sarah Jane Adventures was officially announced in a press release on February 6th. Successfully auditioning to play Rani was Anjli Mohindra, who had appeared in episodes of Doctors and Coronation Street. Former The Thin Blue Line co-star Mina Anwar was cast as Gita. The role of Haresh went to Ace Bhatti, who had been a regular in programmes such as Cardiac Arrest, Grease Monkeys and New Street Law. The Chandra family would be introduced in the second story of the 2008 season, which was one of the scripts allocated to Ford. This became The Day Of The Clown, for which he took the opportunity to bring back the Pharos Institute and Professor Rivers, played by Floella Benjamin, as previously seen in The Lost Boy.

The basis for Ford's story was the legend of the Pied Piper of Hamelin, a town in Germany. In 1284, it appears that the children of the town were lost in some manner, and local lore associated this event with the figure of a piper dressed in many colours, whose image appeared in a stained-glass window installed in the Church of Hamelin around 1300. Although the church was destroyed in 1660, independent records supported the window's description. Subsequent retellings added the idea of the Piper having been hired to rid Hamelin of a plague of rats using supernatural powers, only for the town's mayor to renege on his remuneration, thereby inspiring the Piper's revenge by stealing away Hamelin's children. The legend was famously retold in prose by the Brothers Grimm in 1816, and in verse by both Johann Goethe in 1803 and Robert Browning in 1842.

Due to Paige's limited availability, The Day Of The Clown was paired with the following serial, Secrets Of The Stars, as 2008's first production block. Assigned to direct was Michael Kerrigan, a veteran whose previous credits included the 1989 Doctor Who adventure Battlefield. Cast in the triple role of Odd Bob, Elijah Spellman and the Pied Piper was Bradley Walsh, a former footballer who had successfully established himself as a comedian and then as a television presenter, before beginning to take dramatic parts including a two-year stint on Coronation Street. A decade later, Walsh would portray Graham O'Brien, companion to the Thirteenth Doctor, in Doctor Who.

Production on the second season of The Sarah Jane Adventures began on April 14th, which was also Mohindra's first day of filming. From the 14th to the 16th, the team was based at the programme's regular Upper Boat Studios production home, with the first two days spent on the set for Sarah Jane's attic. April 16th saw the debut of the new set for the Chandra -- formerly Jackson -- residence, replacing the house on Clinton Road in Penarth which had been employed during the first season. Clinton Road was still being used for Bannerman Road exteriors and for the interior of the rest of Sarah Jane's home, however, and it was the site of work on the 17th and 18th. Amongst the clowns seen on Sarah Jane's laptop was Carmen Silvera as Clara, one of the sinister playthings of the eponymous villain in the 1966 Doctor Who serial The Celestial Toymaker.

After the weekend, it was back to Upper Boat on April 21st, for further scenes in the Chandra home, as well as the flashbacks involving the young Sarah Jane. Work the next day began in Tredegar, where the Pharos Institute was again represented by the Vittac Building in the Tredegar Business Park, as with The Lost Boy. Cast and crew subsequently returned to Upper Boat for shots of Sarah Jane smashing Spellman's mirrors. The cameras were rolling at another familiar location on April 23rd and 24th, with Cardiff High School once again posing as Park Vale Comprehensive; the latter day also included the sequence of Luke and Clyde losing Odd Bob in an alleyway off nearby Windermere Avenue. The 25th was spent back at Clinton Road.

The major location for The Day Of The Clown was the Paget Rooms in Penarth, which served as Spellman's Magical Museum of the Circus. Kerrigan's team was at work there from April 29th to May 2nd. The last day also saw the filming of Luke's call to Sarah Jane on Station Road, and Odd Bob distributing his tickets at Penarth Station, a scene which was originally set at a shopping mall. The remaining Park Vale sequences were completed at Cardiff High School on May 5th, leaving just a few inserts to be recorded at Albert Crescent in Penarth on the 13th, and at Upper Boat on the 16th and 19th.

• Doctor Who Magazine Special Edition #23, 24th December 2009, “Episodes 2.3/2.4: The Day Of The Clown” by Andrew Pixley, Panini Publishing Ltd.