Sarah Jane has a surprise for Luke: she's been secretly dating a man named Peter Dalton, and has accepted his proposal of marriage. Luke is delighted to see his mother so happy, but Clyde and Rani are suspicious -- especially when it turns out that nobody has lived in Peter's house for several weeks. They're unable to convince the others that anything is amiss, however, and the day of the wedding quickly arrives. But Peter does indeed harbour a dark secret: he is a pawn of the Trickster, and not even the arrival of the Doctor may be enough to spare Sarah Jane.

Ever since The Sarah Jane Adventures was conceived, there was hope that the Doctor -- then in his tenth incarnation, as played by David Tennant -- would appear in the spin-off. During 2008, Tennant confirmed that he would be interested in participating in the programme's third season, which would be recorded around the time that he was finishing up his tenure on Doctor Who. In planning the 2009 season of The Sarah Jane Adventures during late 2008, it was intended that the Doctor would show up in the season finale, with the idea that he would be drawn back into Sarah Jane's life by her unexpected decision to get married.

The serial was assigned to Gareth Roberts, with the suggestion that the villain of the piece would prove to be the Trickster. Roberts had conceived the time-bending entity for 2007's Whatever Happened To Sarah Jane?, and had then brought him back in the following year's The Temptation Of Sarah Jane Smith. Roberts also had substantial experience writing for the Tenth Doctor, having contributed three scripts during Tennant's time on Doctor Who -- most recently the Easter special Planet Of The Dead, which he had co-written with Russell T Davies, the executive producer of both Doctor Who and The Sarah Jane Adventures.

In addition to the Doctor and the Trickster, it was also planned that the story would bring back Brigadier Lethbridge-Stewart

In addition to the Doctor and the Trickster, it was also planned that Roberts' story would feature Brigadier Alistair Lethbridge-Stewart. Portrayed by Nicholas Courtney, the character had a long history in Doctor Who dating back to 1968's The Web Of Fear, and had most recently appeared in Enemy Of The Bane, the 2008 finale of The Sarah Jane Adventures. Courtney was enthusiastic about the prospect of joining Tennant on-screen, as he prided himself on the fact that the Brigadier had met the first seven Doctors during televised adventures, and encountered the Eighth Doctor in audio dramas released by Big Finish Productions.

Roberts' original version of the scripts -- dated January 7th, 2009 -- featured a framing device in which Clyde Langer commented on the events of the story from limbo. The Brigadier was joined by his wife Doris, whom Angela Douglas had played in the 1989 Doctor Who adventure Battlefield. In the first episode, the Brigadier counselled Clyde about his resistance to change, before joining the Doctor and the Bannerman Road gang in opposing the Trickster during the concluding installment. At this point, Sarah Jane's fiance was called Peter Cawston, while the Registrar -- unnamed in the broadcast version -- was Yvonne Pritchard. The creature in the parcel was called a Metracton at this stage; this part of the plot was drawn from a discarded element of the programme's very first episode, 2007's Invasion Of The Bane, involving an alien Gloor. In the end, the Metracton was replaced by Travast Polong, previously seen in 2008's The Mark Of The Berserker.

When discussing the Pantheon of Discord, the Doctor originally referenced various other members whom he had encountered during his adventures. They included the Guardians (two of whom, the Black Guardian and the White Guardian, had been the driving forces behind the quest for the Key to Time which began in 1978's The Ribos Operation, before reappearing for a trilogy of stories in 1983 starting with Mawdryn Undead), the Graskes (who had assisted the Trickster in both of his previous appearances), the Reapers (from 2005's Father's Day) and the Time Beetles (from 2008's Turn Left, in which the Doctor had referred to them as being members of “the Trickster's brigade”).

It became clear that David Tennant would not be available during the final recording block

As planning progressed, it became clear that Tennant would not be available during the season's final recording block in July. Instead, Roberts' serial -- eventually known as The Wedding Of Sarah Jane Smith -- would be made and broadcast third, providing a major mid-season attraction. Similarly, The Mad Woman In The Attic, which was intended to serve as the year's penultimate adventure, was brought forward to be the season's second story. It incorporated elements -- such as the return of K·9 -- which would set up the Trickster narrative. As such, The Wedding Of Sarah Jane Smith had to be carefully structured to limit the involvement of Luke Smith, due to the timing of Tommy Knight's GCSE examinations.

A few weeks before recording was to begin on the new season, the production team received the unfortunate news that Courtney's ill health would not permit him to travel to Cardiff to film The Wedding Of Sarah Jane Smith. This was confirmed on April 2nd, resulting in the Brigadier's removal from the action and the inclusion of a line of dialogue which indicated that he was in Peru, much as in the 2008 Doctor Who adventure The Sontaran Stratagem / The Poison Sky. It was now known that The Wedding Of Sarah Jane Smith would represent the final filming of Tennant's tenure as the Tenth Doctor, although its broadcast would preceed his last two Doctor Who stories: The Waters Of Mars and The End Of Time.

The Wedding Of Sarah Jane Smith was directed by Joss Agnew, and indeed the first recording for the story took place while Agnew was still working on his preceding assignment, the season opener Prisoner Of The Judoon. This included shots of Sarah Jane behind the wheel of her car on Royal Close and Paget Road in Penarth, captured on May 1st, and material in Luke's bedroom, taped at the show's regular studio facilities in Upper Boat on the 5th. Principal photography officially began on May 15th, a day spent at Upper Boat on the attic set. However, production on The Mad Woman In The Attic was still ongoing, so filming for The Wedding Of Sarah Jane Smith did not resume until May 21st, when Clinton Road once again stood in for Bannerman Road. Various sets were in use at Upper Boat on the 22nd, including the attic, the limbo and the Chandra home; effects inserts were also captured.

Tennant joined The Sarah Jane Adventures on May 25th, having just finished recording his final Doctor Who story. His first day on the programme was spent at Upper Boat for scenes in the TARDIS console room and in Sarah Jane's attic, prompting a press release from the BBC the next day to confirm Tennant's appearance in the spin-off. Meanwhile, Tennant had travelled with the cast and crew to the serial's major location, Court Colman Manor in Pen-y-fai, for filming from May 26th to 29th. Built in the mid-eighteenth century, Court Colman Manor had been a private residence for more than two hundred years before being converted into a hotel; it had previously been the venue for the wedding of Gwen Cooper and Rhys Williams in Something Borrowed, a 2008 episode of Doctor Who's other spin-off, Torchwood. For The Sarah Jane Adventures, it would likewise become Gerrard House, the site of Sarah Jane and Peter's nuptials. In addition to Tennant, the cast was briefly joined at this point by Zienia Merton -- one of Doctor Who's earliest guest cast members, having played Ping-Cho in Marco Polo back in 1964.

On May 29th, Tennant's week of work on The Sarah Jane Adventures -- and the era of the Tenth Doctor in production -- drew to a close with the scene of the Doctor exhorting Clyde and Rani to follow him upstairs. May 31st was a rare Sunday in the shooting schedule for The Sarah Jane Adventures. Agnew's team was based in Llandaff, first for sequences in Peter's house -- actually a private residence on Palace Road -- and then at Mulberry Street Restaurant, for Sarah Jane and Peter's date. Then it was back to Colman House Hotel on June 1st and 2nd; this work included Peter's proposal to Sarah Jane, which was recorded in the hotel restaurant.

When The Wedding Of Sarah Jane Smith aired on October 29th and 30th, it became part of the year-long build towards Tennant's exit from Doctor Who, which was generating enormous interest nationwide. This helped The Sarah Jane Adventures achieve its highest ratings since its debut with 2007's Invasion Of The Bane, effectively doubling the audience which had watched the 2009 season's first two stories.

• Doctor Who Magazine Special Edition #28, 13th July 2011, “Episodes 3.5/3.6: The Wedding Of Sarah Jane Smith” by Andrew Pixley, Panini Publishing Ltd.