As I am leaving Jane Gardam’s home in Kent I notice a lacrosse stick hidden among brollies and walking sticks in a bucket by the staircase. “That was my daughter Kitty’s,” the 87-year-old author tells me. She adds: “I should probably get rid of it.” Her voice has the age-ground fragility of those who have outlived too many loved ones, especially children – Kitty, an esteemed artist, died, aged 52, four years ago.

It has been an afternoon populated by ghosts. Gardam, though best known for the glory-laden Old Filth trilogy, will this evening be awarded the prestigious Charleston-Chichester Award for a Lifetime’s Excellence in Short Fiction, at the Small Wonder Short Story Festival at Charleston. She is the first English author granted the accolade and a worthy recipient: lucid and closely observed, like her novels, her short stories are rich and vivid. This is the latest honour in a career that has included two Whitbread Prizes and an Orange Prize, as well as countless other international awards. Though visiting her to talk about her shorter fiction, including her last collection The Stories, published by Abacus, it is Gardam’s dead – her parents, her husband and daughter – who haunt the interview.

Not just the interview: departed spirits surround us. On the walls of her manor house, a one-time pilgrims’ hostel that became the Gardam family home in 1987, hang paintings by her QC husband David, who died of Alzheimer’s in 2010, as well as Kitty’s exquisite flower illustrations. Family photographs cover tables and desks – including one of David looking rascally in a judge’s wig. As we talk, her dead father, mother, and brother enter the room.

Not that this isn’t a jolly couple of hours: Gardam, as her legion of fans knows, has a sharp satirical eye – her work has drawn comparison with Jane Austen – and laughter peppers our conversation. About the Second World War, she proclaims: “I was in wild excitement.” Then, eyes glinting, confesses: “It was extraordinary. I remember laughing in the air raid shelter once because the curate had been killed the day before and my mother came in and said that ‘I believe the gentlemen’s club has been struck in Coatham High Street’.” She looks at me, devilish. “Because I knew the vicar was likely to be in the club, I said: ‘Ooh there might have been a vicar and a curate in one week’.” Her laugh is loud and clear, strong. “My mother and father almost turned me out into the cold.” Sheepishly, she adds: “What a dreadful thing to say.” Then lets rip a peel of laughter.

Though she is a child of Yorkshire, the dark, harsh landscape of Cumberland formed her, thanks to a schoolmaster father born of West Cumbrian farming stock. While Gardam recalls a strict family life in Yorkshire, summers spent at her father’s parents’ farm were joyous wild excursions away from adult control. Here she listened to the stories of her elders while the cadences of the local dialect – of which she does a very passable impression – developed her ear for language.

Her parents were a huge influence. “My mother was very much deprived of an education and believed in stories being tremendously important.” Pained by sciatica, Gardam winces and shifts in her seat. Memories of her mother are vivid, tinged by magic – a four-year-old Jane looks over her mother’s shoulder and for the first time understands that the black marks on a page tell tales; an 11-year-old Jane gazes through a window as her mother reads and a Messerschmitt flies so close she sees the pilot’s head.

Her father, meanwhile, had a talent for nicknames, which his daughter inherited – she rivals Amis and Dickens for apt nomenclature. As she describes him, he sounds a likable man of deep but quiet emotion. The story “Lunch With Ruth Sykes”, about a mother and daughter, made him cry. “He came to the end and flung it away, crying, ‘oh God!’.” She laughs as she mimics him.

Unlike most writers of Gardam’s longevity, she was a late starter. Words “burst” from her on to the page on the day her last child left for school. She was 40 years old. A conventional 1950s stay-at-home mother, she had longed to write, but adds: “I wanted to have children, so I married and looked after them.” I raise the question of the pram in the hallway, but she resists anything that may imply criticism of her children or husband. They were no impediment, it was what she chose. She adds less convincingly that she bet on having the time to write: “I come from a family of long livers.”

Late starter she may be, but Gardam has been prolific: her backlist spans nine short story collections, 10 novels, 12 children’s books and nine books of non-fiction. All this from a self-confessed “slow” writer. Her productivity is matched only by the breadth of output, from dramas of domestic detail to fantastical stories and end-of-Empire epics. All are present in The Stories. Did she ever wish to stay in one genre? “No. I just wrote what came into my head,” she answers flatly. The truth is, though, she has had more fun skittling from one format or style to another.

Her dislike of categorisation is most clear when I ask her which she prefers: novels or short stories. “Short story is a terrible term, I much prefer the French term conte.” For the first time, a note of irritation enters her voice. I have clearly found a sensitive spot. “I looked up the word ‘short’ in the OED, and it is almost always used pejoratively,” she adds sniffily. “Short stories are nearer poetry than anything. They are like a conversation, a dialogue. And besides, some of them are quite long.”

Her dislike of categorisation is in part because there is no sharp divide in any of her writing, one flows into another. This is made obvious with “The People on Privilege Hill”, the end piece in The Stories collection. The first outing for Edward Feathers, better known as Old Filth and the central character to the trilogy that bears his nickname.

An Edwardian-looking man spotted in the street inspired the story. “I thought he was a ghost, he looked so out of place. David pointed out that a real Edwardian would never be seen out without a hat, so he couldn’t have been a ghost.” A shake of the head and that laugh again: “But I am still not entirely sure.”