One of the biggest goldfish I’ve ever seen is swimming about in a bowl in Deborah Hutton’s kitchen. Her daughters Clemmie, 12, and Romilly, 15, are curled up nearby watching television. At the top of the stairs nine-year-old Freddie is splashing about in a bath and shrieks hello as I wander past to the next-door bedroom.

I have come to talk to the children’s mother, who is propped up in bed against a mound of pillows. Eight months ago Hutton, a former health editor of Vogue, was diagnosed with advanced inoperable lung cancer after she had sought treatment for what she thought was a minor nagging cough.

The diagnosis came as a total shock not just to Hutton but to everyone who knows her. Before the cancer she was not just a busy writer and mother of four (her older son, Archie, is 17) but a superfit half-marathon runner and yoga enthusiast who had smoked only briefly in her teens and early twenties.

It soon became clear that her situation was dire. So bad was the prognosis that her consultant told her she should not look up her kind of cancer on the internet as she would only terrify herself.

Hutton, 49, had to come to terms with the fact that all the milestones in her life that she had taken for granted — the children’s graduations, their weddings, the birth of their children — she would never get to see. But, more importantly, she had to work out how best to protect them. That has meant trying — despite her now weakened state and the oxygen tank she relies on to help her through bouts of breathlessness — to keep the atmosphere at home as normal as possible.

“This is a happy house,” she says firmly. “I love having the children and the dog and cats racing in and out. I want a home full of laughter and happiness and not a sad, dark place where someone’s got advanced cancer. It’s full of busyness and bustle and ongoing life.”

Right from the start she and her husband, the photographer Charlie Stebbings, decided to be open about what was happening. “Romilly said, ‘Mummy, the day I hear the words “all clear” will be the happiest day of my life’. It was a brutal moment. I had to decide whether to dissemble and decided not to. I told her this was the kind of cancer where you don’t hear those words. It’s something we all have to learn to live with.

“Some people never tell their children and I can completely understand that,” she says. “If you have stage one breast cancer, why worry your children? You might end up dying of Alzheimer’s at 80.

“That was never an option for me. So we had to see it as taking the children on a journey. I told them there would never be any closed doors, never any whispering, there would never be anything they weren’t told that was frightening because it’s more frightening to feel you’re excluded.

“Friends have told me they were not taken on that journey: it wasn’t what you did when we were kids. They were just told Mum or Dad wasn’t well, they had a lump and it was getting better. Then the parent died and they were left with desperate scars that never healed.

“I hope it will be different for my children. It can’t ultimately be anything but traumatic and awful but given that, we want the time we have together to be full of laughter and love and not full of words people can’t say.”

One of the first things that struck Hutton in the wake of the diagnosis was the sense of shock and helplessness among her friends. People wanted to help, but didn’t know how.

“Some people have a gift for this sort of thing,” she says. “A QC, a close friend and one of the busiest people I know, called as I was just about to be given the bad news and, not expecting the test results to be ready so soon, I had arranged to meet my 15-year-old daughter, who already suspected something was badly wrong.