Goodnight Sweetheart is a British science fiction time travel sitcom, starring Nicholas Lyndhurst, created by Laurence Marks and Maurice Gran, and produced by the BBC. The sitcom is about the life of Gary Sparrow, an accidental time traveller who leads a double life through the use of a time portal, which allows him to travel between the London of the 1990s and the London of the 1940s during the Second World War.^[2] The sitcom's creators, who also created Birds of a Feather and The New Statesman, wrote most of the plots for the episodes.^[3]

The sitcom premiered on BBC1 on 18 November 1993 and ran for six series until its conclusion on 28 June 1999, with repeats after this date being aired on ITV3, Gold, Drama, Yesterday and Forces TV on Sky Digital. Lyndhurst's involvement in the sitcom allowed him to win the Most Popular Comedy Performer at the National Television Awards in 1998 and 1999.^[4] On 2 September 2016, the sitcom received a one-off special entitled Many Happy Returns, following events after the final episode.^[5] The sitcom itself later received a musical adaptation in 2017.

Goodnight Sweetheart is about the life of Gary Sparrow (Nicholas Lyndhurst). In 1993, Gary works as a TV repairman, who struggles with his life and the marriage to his ambitious wife Yvonne. He is best friends with Ron Wheatcroft, a printer whose marriage is on the brink of collapse. On attending a TV repair call-out in London's East End, Gary accidentally discovers a time portal at Duckett's Passage, which leads to war time London, where he meets Phoebe Bamford, a pretty barmaid who works in the "Royal Oak" pub; her father Eric who runs the pub; and Reg Deadman, a dim-witted but friendly policeman. Gary strikes up a relationship with Phoebe. He finds he can use the time portal to travel between the 1990s and 1940s, and he uses it to continue seeing Phoebe. To ensure his visits do not interfere with history, Gary brings in assistance from Ron as a confidant, to aid him with problems and to supply him with 1940s five-pound notes and identity documents.

Gary soon finds himself leading a double life. When visiting Phoebe, he explains his absences through working as a secret agent, using his knowledge of future wartime events to his advantage in the deception, while also claiming to be a singer-songwriter, passing off modern pop songs as his own and supplying many items from the present that were rationed in wartime Britain. When with Yvonne, Gary initially claims his absences to be major call-outs for his work, but after losing his job in 1995 to buy and run a shop called "Blitz 'n' Pieces" – selling goods he acquires in the 1940s as rare memorabilia, to maintain access to the time portal in the present – he uses it to lie that he has to be absent to conduct buying trips for stock.

Over the next five years, Gary's life is further complicated by his relationships with the two women. Phoebe eventually takes over the running of the Royal Oak after the death of her father Eric, later marrying Gary, despite his committing bigamy. (Although Gary rationalises this with the technicality that — because of his continuing travels between eras — he isn't married to two women at the same time.) His marriage with Phoebe results in a son, Michael. Gary moves into a luxury flat in Mayfair, with Reg becoming a doorman in their building after retiring from the police. Yvonne becomes pregnant, only to suffer a miscarriage, but she later becomes successful with her organic beauty products, opening a company and transforming into a millionaire, allowing her and Gary to own a luxury apartment. Ron later faces a divorce, losing both his home and control of his printing company, adding to Gary's problems, who^{[clarification needed]} eventually allows him to have the lease for his Mayfair flat in the present. During his time in the past, Gary has encounters with several historical figures, including Winston Churchill, George Formby and Noël Coward, while also dealing with some of the peculiar effects of time travel during various trips.

Goodnight Sweetheart eventually concludes in 1945 during VE Day. In 1999, Yvonne becomes suspicious of Gary's frequent absences and follows him to the shop, where she witnesses his disappearance through the time portal. Gary later becomes trapped in the past when the portal closes after he saves Clement Attlee from an assassination attempt by poisoning. He later deduces that it was his destiny to travel back in time with the purpose of saving Attlee's life and the portal closed because he had fulfilled this purpose. Gary is resigned to being forced to stay with Phoebe and their son, though he writes a message behind a strip of wallpaper of his Mayfair flat, knowing that Ron is redecorating it in 1999. Gary's writing appears before Ron and Yvonne in real time, advising him to tell Yvonne everything. He does so off camera and Yvonne advises him that she no longer wishes to have any contact with him, which he accepts.^[how?] The final episode of the original series cuts to Yvonne standing at the gates of Blitz 'n' Pieces, wondering whether or not they would meet again, before being joined by Ron. In 1945, Gary is standing in Duckett's Passage, wondering the same, before being joined by Phoebe and Michael.

A total of 59 episodes were made, including a Christmas special in 1995 and a special in 2016. Marks and Gran, the creators, wrote the first series; many later episodes were written by other writers. As in Marks and Gran's sitcom Get Back, most episodes of Goodnight Sweetheart — and the programme — were named after popular song titles, others being derived from film titles. The show is named after the song "Goodnight, Sweetheart", a popular song of the 1930s and 1940s, popularised by Al Bowlly in 1931; it was later sung by Nick Curtis as the series signature tune. During one episode Gary and Phoebe refer to Bowlly's death during the Second World War. Because of a script-editing error, two episodes (series one, episode six and series four, episode two) were both titled "In the Mood". There is no special connection between these two episodes.

All six series and the 1995 Christmas Special have been released on DVD in the UK (Region 2) with edits made to certain episodes, the Christmas special was released on the third series DVD. The first five series have been released in Australia (Region 4).

• Although the 2016 special "Many Happy Returns" has not been released onto DVD, it was released digitally in September 2016 on BBC Store.^[6]

The show's writers and producers have stated they have received thousands of emails and letters regarding the show wishing for its return to the small screen. Laurence Marks and Maurice Gran have both stated that while there are no plans to bring the series back, it might possibly come back if the musical is made and is a success. On 5 July 2016 it was announced that the show would be returning to BBC One for a one-off special, as part of the BBC's "landmark sitcom season". Unlike the original series, which was filmed in London, it was filmed and produced at dock10 studios, in Salford Quays. Marks and Gran wrote the script and Lyndhurst returned to the role of Gary Sparrow.^[7] The special episode aired on 2 September 2016 on BBC One. It received a positive response.^[8]