The prolific playwright and screenwriter, whose numerous Christmas plays are a staple of the festive theatre circuit, had been working on another piece, which, by his own admission, "was going nowhere."
"This one sort of crept up on me. I was going to the theatre a lot, and not really enjoying it.
"I saw plenty of ideas there, but what I wanted to do was something that was simple and human, and that wasn't just about words and dialogue, but was more about the sound of words as well."
Cars and Boys tells the story of Catherine Miller, the ageing matriarch of a big-time haulage company who has been calling the shots all her life.
Even after she suffers a stroke and is confined to a hospital bed, it seems Catherine is determined to take charge of everyone and everything around her.
"It's about the life of a business," says Paterson. "It's a play about power and endeavour, and the language of business, which has a vitality to it. If it becomes fractured when the main character in the play has a stroke, she can reveal things that she wouldn't ordinarily reveal.
"We're not doing Holby City, but while it's always dangerous to use the word poetic, the stage is poetic, and you have to try to find a language to express that."
There is an umbilical link between Cars and Boys and Paterson's 1999 play, King of The Fields, which first appeared at the Traverse Theatre in Edinburgh.
That play featured a couple at its heart who, while they don't appear in Cars sand Boys, are the parents of Catherine, and ran the haulage firm before her.
"Philip keeps teasing me that this is part two of a trilogy," says Paterson, "but writing the play like that happened without me ever pre-planning it."
Given that Ayrshire-born Paterson's own father ran a haulage business, Cars and Boys sounds close to home, even though Paterson points out "the play is completely fictitious".
"As with King of the Fields, it's rooted in family in a way that enables me to use phrases and bits of language that are quite private, so sometimes it's hard for me to listen to, but because of my repressed Calvinism, I couldn't out my parents onstage. One of the reasons I'm a playwright is because I can express emotions which might otherwise find difficult to do so in life.
"Although it was expected of me to take over my father's haulage firm, I never really wanted to, but it's always in my blood."
Cars and Boys will be staged with the audience sat in a transverse seating arrangement on Dundee Rep's stage in a way that effectively creates a temporary studio theatre more suited to Paterson's play.
Such scaling down of the Rep's auditorium has previously been utilised for productions of Howard Barker's Scenes From An Execution and Euripides' Greek tragedy, Hecuba, while a staging of Tom McGrath's play Kora took place in a building behind the theatre.
"Cars and Boys is a play that will benefit from intimacy," says Paterson, "so staging it in this way suits the play."
Beyond Cars and Boys, Paterson is working on a screenplay based on Dr Glas, a 19th century set novel by Swedish writer Hjalmar Soderberg.
While a new children's play may be forthcoming, for now, at least, it is the very grown-up world of Cars and Boys that is on Paterson's mind.
"It's always interesting to look at someone who's had power in their life, and is still trying to hang onto that power no matter what," he says.
"There's a lot about love in Cars and Boys as well, but it's a play about someone who is absolutely fighting to survive, and it's a bare knuckle fight between her and death itself.
"You know that if he came into the room, one thing for certain is that she wouldn't be afraid of taking him on."
Cars and Boys, Dundee Rep, April 11-26. www.dundeerep.co.uk