THE serendipity of a conversation overheard at an office Christmas party helped Ali Carter land a three-book deal. It all came about when the Forres-born artist-turned-author joined her husband for festive drinks with his publishing colleagues at a Soho pub in London.

Carter, 35, got chatting about her work as a pet portraitist to the head of sales. "She said: 'Oh, will you draw my husband's dog?' Listening in to our conversation was the crime fiction editor who then got very excited about the idea of a series involving pets and murder.

"I left the party and said to my husband: 'I'm going to get us a book deal'. That Christmas I wrote a few chapters about an artist who draws pets and solves murders."

And with that the Susie Mahl mystery series was born. Carter's debut novel, A Brush With Death, is published this month billed as "Miss Marple meets Downton Abbey".

The cosy crime read charts the adventures of an artist-meets-amateur-super-sleuth attempting to solve the riddle of how a wealthy earl met a grisly end with his trousers down in a village graveyard.

Carter sums it up as "an escapist, light-hearted and humorous poke at the British class system". Books number two and three are already in the pipeline with East Sussex-based Carter the first to admit that it's all been a bit of an unexpected whirlwind (or in her words "incredibly fluky").

"The embarrassing thing is that I had never read an Agatha Christie before I got the deal," she says. "I have now read lots and really use her as my role model. I wish Miss Marple was younger, but I think she is a very good, stable main character. I find Agatha Christie very amusing."

Her day job is as a fine artist specialising in oil paintings from life with an emphasis on colour. "It is mainly still life and landscapes," she says. "It sounds pretentious, but I am trying to capture a moment of calm."

Carter is also much in demand for pet portraits which is where the lines of life and art blur slightly. In fact, there are a few similarities between her and main protagonist Susie Mahl.

"Well, I like to try and tell my mother it is definitely not me and not my family …" she says, laughing. "But yes, Susie lives in Sussex, I live in Sussex. We're both fairly alike and I have had great fun developing her character in a way that mine isn't. She gets her paintings in places I never get in."

In the book, Susie dabbles in pet portraits to subsidise a "penchant for expensive underwear". Is that a semi-autobiographical nugget sneaking in there too?

"I always find buying underwear, the really lovely stuff is so expensive," says Carter. "You can never quite justify spending what you would like to on it. So, I always think that if one had masses of money what fun to be able to buy your favourite underwear."

Despite the old adage of never work with children or animals, Carter clearly enjoys her chosen profession. Do the animals sit for her or does she paint them from photographs?

"What I do – much like Susie – is to meet the pet otherwise you never see their character," she enthuses. "It is important for me to see how the owners interact with their pets too. I spend quite a lot of time with them doing drawings and taking photographs.

"I'm a real troubled artist, I go through great pains. My husband will say: 'Oh, you just are going through that stage of thinking it is no good …' People love their pets and if you can really capture it, they are so happy."

The middle of three children, Carter spent her early childhood near Girvan in South Ayrshire. Her father Jonathan Warrender is an artist known for his landscape paintings, while her mother Fiona runs the family farm.

Carter studied art history at St Andrew's University and after graduating embarked on an eclectic career path that included a stint in investment management and retail.

"I never enjoyed it," she reflects. "You do earn good money – I have never earned so much money as I did in my first two years after leaving university – but it is long hours and you think: 'What on earth am I doing this for?'"

The next milestone was co-founding video production start-up "We made marketing videos for people to put on their websites and information videos for anything from cosmetic surgery to training your dog," she recalls.

But life changed irrevocably when Carter had a catastrophic cycling accident in 2011. She required major brain surgery and underwent a lengthy recovery period.

"I came off a bicycle in London," says Carter. "It is unknown what happened, but the big thing was that I got a blood clot between my brain and skull. It wasn't identified to begin with because I seemed to be making complete sense."

She was taken to hospital and kept in overnight. The next morning Carter told a nurse that her head didn't feel right. "They did a scan and found I had been bleeding for nine hours," she says. "Then they went into overdrive and I had major brain surgery.

"My poor mother came down from Scotland and was told either I would be brain damaged or not get through it. Miraculously I got through it and wasn't brain damaged.

"It did take an awfully long time to recover. Until I could spend a lengthy day awake, it was about two years. Now I suffer from chronic fatigue, so I couldn't have a 9 to 5 job. I get migraines and various other issues, but I'm so lucky to be alive."

As part of her recovery, Carter set herself the challenge to walk solo from Canterbury to Rome, a three-month pilgrimage covering more than 1,200 miles (2,000km).

"I knew I would never go back to my old life, so I needed to work out what I was going to do," she says. "The only thing I could do was walk. I set off in July – I'd had my accident in February – and thought I would just walk and do however long a day that I could.

"I didn't want to see lots of people. I had a telephone I could call out on, but that people couldn't call in on. I was on my own wandering. I became desperate to have a solution for life by the time I arrived in Rome. And luckily, I did. I thought: 'I will go to art school.'"

Carter attended a Fine Art Foundation Year and Drawing Year, both at the Royal Drawing School in London. It was a vocation she had railed against as a youngster. "My father made the mistake of telling me that I should be an artist. I didn't do art GCSE or A-level, so I came to it late."

She alludes that her formative years weren't always content. "I went to boarding school aged eight and I never forgave my parents. I do think they did it with the best interests in mind for education, but it was too tough on someone like me who loved being at home."

To that end, Carter paints a picture of herself as a child often at odds with the world. "I was quite quiet and solitary," she says. "I had friends but I'm not somebody who needs to be around friends. I still write letters rather than ring people up.

"I was competitive with myself. If I saw a hill, I would want to get to the top of it. I played squash throughout school and university. I would like to have played professionally, but my parents told me that with sports people, you damage your knee and it's all over."

Her schooling was far from conventional. "I had an unusual education. I went to five schools. I went to an all-boys Catholic school in Yorkshire for sixth form which my brother was at. My parents thought it would be much easier if I was in the same place. They asked the school and they said yes."

What was it like going to an all-boys school? "Absolutely awful. I moved from Fettes in Edinburgh which I loved. It is too unfair to blame the boys, but they didn't want girls in the school, so they weren't very nice. There was no sport for girls, although I did get into the boys' first squash team so that really showed them up."

Why did she leave Fettes? "I was quite naughty," says Carter, biting back a giggle. "Boys. Alcohol. Cigarettes. But I also worked quite hard, so it was a complete confusion for my school. I was always in trouble. My parents thought it [the all-boys school in Yorkshire] would be a fresh start, but what a weird place to send me.

"Fettes was GCSE and Yorkshire was A-Level. I did two years at each. I also went to an all-girls school in Yorkshire for two years before my GCSEs. But I didn't like being all-girls. I was at a prep school in Perthshire for two years and a local school in Barr near Girvan for two years."

These days home is at the foot of the South Downs with her husband Sam, 43, a non-fiction book editor. The fierce competitive streak that once flourished on the squash court has been transferred to the kitchen. "My husband and I both love to cook and are very competitive with our cooking," she laughs.

But mostly it's rustling up food purely for enjoyment. "I would make mayonnaise rather than buy it," says Carter. "I bake bread. My parents live on a farm, so we tend to drive up at Christmas and then drive back with the car full of meat. We have a vegetable garden."

It is her hope that the world of Susie Mahl will keep her busy too. Carter isn't short on plot ideas. "If Susie becomes popular – and the books sell – Susie could go on and on."

A Brush With Death by Ali Carter is published by Point Blank, priced £8.99