As the British director and screenwriter of Now is Good, a drama about a young woman with leukaemia, he could often be found fleeing his study and appearing before his family damp-eyed and distressed "My wife would be like, 'What, again?'" he recalls.
Then there was the test screening at which several busloads of teenagers proceeded to cry a Thames, a Clyde and a Seine. "It was amazing, like something had been released into the cinema."
Now is Good is in the great tradition of weepies, those three-handkerchief numbers that stretch from Imitation of Life to Love Story to Dear John. Now is Good stands out in that it is British, and therefore goes about its business with a clear-eyed gaze and some humour. Even so, an equally clear-eyed Parker expects not everyone will fall hard for this modern Love Story. "I'm sure we'll get slaughtered by some journalists."
Parker, best known previously for adapting the comedy drama The Best Exotic Marigold Hotel and directing Imagine Me and You (a rom-com) and Loved Up (a drama about the rise of Ecstasy), took some persuading when the producers of Best Exotic pitched it to him initially. He thought the idea sounded engaging and moving but maybe wasn't "my bag of chips". They asked him to keep an open mind and read it. He did, and texted the producers at 2am to say yes.
Casting was critical to getting the right tone for the film. The very English heroine, Tessa, is played by Georgia-born Dakota Fanning. Given the sometimes awkward history of American actors playing British parts (remember the mauling received by Anne Hathaway for One Day), Fanning, like Parker, was moving away from what she knew. As soon as she got the part she started practising the accent. When she turned up on day one of shooting she was ready to go, says Parker.
"We didn't do one extra take for the accent. We had an accent coach on set, but she just sat there twiddling her thumbs and eating biscuits."
Paddy Considine, star of Dead Man's Shoes and Submarine and the director of the hard-hitting drama Tyrannosaur, plays Tessa's father. Getting a yes from Considine was important to Parker, who wanted to make a film that was fast, funny, and truthful.
"One huge demonstration of that was the day Paddy read it and wanted to do it. That was a huge affirmation that I was on the right lines. He doesn't do things that are sappy. He's the definition of a truthful, rigorous actor who doesn't work for a pay cheque."
In both Best Exotic and Now is Good, Parker was working from original novels. Best Exotic came from Deborah Moggach's These Foolish Things, and Now is Good from Jenny Downham's Before I Die. Moggach, a screenwriter herself, was happy to leave Parker to it. "Jenny was slightly different. It's her first book, she was naturally and rightly wary." Some of her suggestions were taken up, some "politely rejected" he says. In the end, she was "lovely about accepting [film] is a different beast".
With a cast, which also included Olivia Williams (An Education, Rushmore), Kaya Scodelario (Skins) and Jeremy Irvine (War Horse) in place, shooting could begin. Again, hitting the right tone was crucial.
When he was writing the script, Parker pinned a quote on his wall from Ronald Harwood, who wrote the screenplay for The Diving Bell and the Butterfly, an adaptation of Jean-Dominique Bauby's autobiography about living with near-total paralysis. Harwood had been asked how he managed to write a script that was moving but never sentimental. His answer: tell the truth.
"Sentimentality by definition is striving for an effect," says Parker. "It's fake. If you are honest then you can break hearts. That was the goal. It's not for me to say whether we achieved it or not but that was the goal."
Parker, the son of a judge, began his writing career at Cambridge, where he read English. To be precise, lift-off occurred in Edinburgh. Any refugees from the recent Fringe who suffered poor ticket sales and wondered if Edinburgh was worth it can take comfort from Parker's tale.
He had written a play, Killers, and put it in a drawer. After it was eventually performed locally, his friend, the comedian Ben Miller, suggested they take it to Edinburgh.
"We drove up there with the set tied very badly to the roof. It took about 14 hours driving because we could only do 20mph."
The first performance was to just four people. But those four turned out to be critics, and they liked the play. "The best reviews I've ever got in my life. Sadly it tainted me," laughs Parker. "I thought it was always going to be like this." Cue toasty reviews, cue bigger audiences, cue agents, and cue the BBC commissioning him to write Loved Up. Well worth coming to Edinburgh then? "Without that I honestly don't think I'd be doing it now."
After Loved Up he went back to school as a writer on Grange Hill, not an experience he enjoyed, largely because it was clear that the show's glory days were over. Everyone would sit around, says Parker, and discuss why people had watched it in the days of Zammo and his troubles.
Following his Grange Hill experience, Parker opted not to write as part of a team for television again. He wrote two more movies, then made his directorial debut with Imagine Me and You in 2005. His next entry on the imdb database is 2011 and Best Exotic. I wonder how he filled that six-year gap. With seemingly glamorous but ultimately unfulfilled writing tasks, it turns out.
"The weird trajectory of a writer is that you can write with increasing success and absolutely nothing ever happens. Paradoxically the bigger films you write the less likely it is to happen. I wrote a film for Paul Greengrass that didn't happen. I wrote a film for Tom Hanks that didn't happen. For Jonathan Demme."
As he says, he was being paid and working, but it was dispiriting at the same time. "There are immensely successful writers in Hollywood that have no credits at all but have an extremely lucrative, successful life ... after a time you start to long for something to actually happen."
Happen they did with first Best Exotic, and now Now is Good. There is talk of a Best Exotic sequel, but for now the next gig for Parker is returning from Vancouver (where his wife, Thandie Newton, is filming) with the couple's two daughters, ages seven and 11. He's also caught up in the US television equivalent of the Lottery, waiting to see if a pilot he has written, Hotel California, about a swanky hotel, will make it any further.
"They commission somewhere between 40 and 50 scripts, of those they make 10 pilots, of those about three get to air, and of those at least one will be cancelled after one episode. I'm one of the 50 at this point."
Still hopeful, then, and no tears just yet.
Now is Good opens in cinemas next Wednesday.