The book is set to be published early summer by Fantom Publishing. Billed as a valuable tool for anyone seeking to write comedy for television, the book contains scripts from six of their series, plus one from a show that was never broadcast.
Reflecting on their writing partnership for the Distinct Nostalgia podcast, Marks said that "we were blessed with really good ideas", and that none bore "any resemblance to the next show".
Elsewhere in the lengthy, two-part interview, the pair, who are set to embark upon their postponed, retrospective tour, Blokes Of A Feather: An Evening with Laurence Marks and Maurice Gran, in September, revealed that they have plans to publish a memoir and criticised the BBC's initiative to revive some of its classic sitcoms in 2016, of which Goodnight Sweetheart was part. However, contrary to previous assertions, they suggested that they still want to bring it back to television
With Nicholas Lyndhurst reprising his role as time-traveller Gary Sparrow, the 2016 episode was commissioned as part of a season to celebrate the 60th anniversary of Hancock's Half Hour's first broadcast, alongside updated versions of the Hancock comedy, Are You Being Served?, Steptoe And Son, Till Death Us Do Part, Porridge, Keeping Up Appearances and Up Pompeii!, although the reimagined Roman sitcom never made it to screen.
The only revival to feature cast members from the original series, which ran from 1993 to 1999 on BBC One, returning to Goodnight Sweetheart had been "great fun, we'd love to still do some" Marks revealed.
Following previews at Romford's Brookside Theatre in 2018, "before Covid happened, we were also on the verge of also doing it as a stage musical. And when all this madness is over, that might still happen.
"But yes, it is a show we had enormous joy making. It was so easy in one respect to write because when you've got two time zones, two periods if you like, your A plot and your B plot are just there for the plucking.
"It's the series, more than any other in Britain, that we get letters, three, four times a week saying 'when's it coming back?'"
Gran explained that "Jon Rolph, the executive producer at Fremantle, he still is very dogged, he says we will get it back. We were a little bit unlucky we're told.
"This may be complete hearsay. But when the BBC very proudly did these reboots, the controller of the BBC went to Edinburgh expecting to get a lot of pats on the back. And instead got savaged for doing remoulds. And so the only show they brought back was [Porridge], Dick [Clement] and Ian's [La Frenais], which we believe they were more-or-less committed to anyway - I think they'd committed to that before they decided to put it in the package."
Transporting Sparrow to the present day and giving him a daughter, the 2016 revival had "embarrassed" the BBC with its "fantastic" reception said Marks.
"Everyone in the press, on social media were saying 'God, we're so looking forward to this series" he said. "And I think the BBC got very embarrassed by the fact that they made the decision [not to commission a series] before they put it out. It got good viewing figures too [4.4million overnight]."
The latest Birds Of A Feather special at Christmas, "goes to prove that anything can come back" said Gran. "I mean obviously, we'll be known as the two old codgers who spend their twilight years recycling their old hits. But I don't care."
The pair's other sitcoms include Holding The Fort, the 1980's "house husband" comedy for ITV, starring Peter Davison, Patricia Hodge and Matthew Kelly; 1991's So You Think You've Got Troubles for BBC One, with Warren Mitchell as a Jewish man living in Northern Ireland and the romantic comedy Love Hurts, which aired on BBC One between 1992 and 1994 and starred Zoë Wanamaker and Adam Faith.
They expressed mixed feelings about the current state of television comedy, pointing to a cultural background of censorship, a reliance on nostalgic list shows and a trend for punching down towards the working-class.
Marks compared the experience of writing sitcoms today to "writing journalism in Stalinist Russia, because there's so much you can't say, there's so much you can't do.
"The number of times you'll hear someone in a position of authority say 'oh, you can't say that'. Well, if you can't say that, you can't write comedy."
Yet he acknowledged that "when you are sat in with a controller, you realise that narrative comedy is so expensive to make, why [would you] make one episode of Goodnight Sweetheart when you could have a series of gameshows?"
What was interesting about Fleabag and Catastrophe, "led by women, is that they don't suffer from that the thing that a lot of other shows suffer from, which is that they're not very funny at all but there's one stupid person in it who's allowed to be funny.
"And when you strip those shows down, although people think they're woke, they're not woke at all because it's mostly middle-class people taking the piss out of the working-class person. Which seems so transparently obvious to me but not transparently obvious to the people who are writing them and buying them.
"So I think there's more good stuff out there than there was maybe five years ago, where what I call the archaeologisation of comedy [became prevalent]. There used to be five comedies a week, instead there were five history shows about the top ten funniest shows involving the word 'gusset' on Channel 5 at nine o'clock. Comedy became a subject of study rather than a subject to renew."
Concluding, he lamented the disruption that the coronavirus pandemic has caused them.
The pair have "two or three" projects in development, including the tour, "quite a meaty memoir which we've pitched", perhaps more Birds Of A Feather and "a couple of other shows in development".
But "a project from scratch, which used to take a year to get an idea on the screen, now takes three years to get an idea on the screen. Well, I've got a marker down in three years time that I intend to be senile. So I don't really want to do something with quite that long a lead period."