Call The Midwife screenwriter Heidi Thomas has told how she keeps the show's scripts hidden away from her husband - despite the fact that he stars in the drama.
Stephen McGann plays widowed GP Dr Turner in the TV hit, alongside the likes of Jessica Raine, Miranda Hart and Jenny Agutter.
The period drama means that the couple, who met after McGann starred in one of Thomas's first plays at the Liverpool Playhouse, are working together for the first time in 25 years.
But Thomas, whose credits include the TV adaptation of Cranford and the recent series of Upstairs Downstairs, told the Radio Times that McGann - the brother of fellow actors Paul, Mark and Joe - did not get to see her scripts before the rest of the cast.
"If he comes into my study while I'm working on them, I cover the screen," she told the magazine.
"But it's wonderful having a project that you can mull over with your partner, although I think our son gets fed up with it."
The opening episode of the second series of the drama, based on the late Jennifer Worth's memoirs and set in London's East End, was watched by 9.3 million viewers.
Thomas said that exhausting all of Worth's stories would prove no barrier to the continuation of the show.
"I will have done (finished Worth's stories) by the end of the second series," she said. "But don't worry. It doesn't mean the show will end.
"The characters will be well developed by then and Jennifer was happy for us to continue."
Thomas, who is also Call The Midwife's executive producer, said that the drama elicited an emotional response from the crew, as well as viewers, with cameramen and electricians always "getting something in their eyes".
She told the magazine: "The edit suite has a wooden floor and was wet after we watched the Christmas special."
Thomas told how bureaucracy can sometimes get in the way when casting babies in the drama.
Babies are "booked" before they are even born because health and safety and BBC guidelines means it can take up to a week after the birth to process the paperwork.
When the babies are older than 10 days, they look too old.
"Sometimes we've had to wrap a baby tightly in a shawl so it doesn't look like a relaxed two-weeker," Thomas said.
She said that the drama owed a lot to CGI (computer-generated imagery) when it came to recreating the look of London's East End in the 1950s.
The crew film on location in a cobbled street then block out modern buildings and give the impression of smoke coming out of chimneys in post-production.
"In episode four of the new series we have a baby born with spina bifida so we used CGI to paint a lesion, a flesh wound on its back," Thomas said, "because you can't submit a newborn baby to a complicated make-up job. It really does make our lives easier."