IF you’ve seen a onesie on TV lately, maybe on a reality show or a charity fundraiser, there’s a pretty good chance it came from The All-in-One Company.

The online business, based in Ashington, has become a go-to for producers, its products having appeared on everything from Dancing on Ice to The X Factor. But if Kate Dawson had followed her instincts one dark December night, it might have been a different story.

“It was just before Christmas and I was the only one left in the office when the phone rang,” recalls company founder, Kate. “It was one of those, do I or don’t I pick it up? I just wanted to get home to my kids. I picked the phone up and it was Channel 4 – would we supply the onesies for Big Brother? That’s where the TV ones started.”

It sparked a meteoric rise for the business, which marks its tenth anniversary this year. Like many success stories, this one started with Kate identifying a gap in the market. “I couldn’t keep my daughter Lilly warm at night,” she explains. “She would wake up every night because she was a little fidget and she would kick the covers off. I needed a fleecy sleepsuit and I couldn’t find one for a child over 18 months of age anywhere. I thought, ‘There have got to be more mums than me looking for something to keep their children warm at night’.”

With onesies now ubiquitous, it’s hard to remember a time when they weren’t available on every high street, but back in 2008, they were practically unheard of. Kate didn’t want just any onesie – she wanted one that met her precise specifications.

“I didn’t want a Babygro that had a hood and feet because I didn’t want her to have a hood on in the cot and I didn’t want it to have feet because I didn’t want to overheat her,” she says. “I thought I needed to create something of my own, so that’s how ‘create-your-own’ was started – because I couldn’t find what I needed.”

Looking at the website, there are literally hundreds of options. You can pick from off-the-shelf designs – maybe the red and black spotty number that Holly Willoughby wore for a charity event – or start completely from scratch, creating your onesie from a choice of fabrics and any number of modifications. The end result is something totally unique – truly onesie of a kind.

“You design your own and personalise it and make it really special,” says Kate, 51. “People want to be unique and have their own identity, rather than buying a mass-produced product. Our onesies are all handmade to order. Everything is hand-cut, hand-sewn, hand-embroidered. People have had them since 2008 and they’re part of the family, they’re like a character.”

Having previously lived in Oxfordshire, Kate moved to Newbiggin-by-the-Sea, in Northumberland, just before starting the business. She’d had several jobs, including running her own nanny agency, but felt the time was right for a change. “My grandparents were in Northumberland and we used to come up every school holiday and visit them and go to the beaches here, which are just to die for,” she says.

“When we had our children, we used to bring them to the beach because we had a holiday home here. Then, when Henry was nine (he’s now 20) and Lilly was six (she’s now 17) we decided to relocate here. Henry was being bullied at school and that was another reason to want to move away.”

Kate couldn’t have picked a better location. With the closure of its sewing factories in the 1980s, Ashington had a ready-made workforce – and it’s thanks to a highly-skilled team that The All-in-One Company can do what it does.

“It’s a manufacturer’s nightmare,” says Kate of mass customisation. “People have said, ‘If you had known how to sew and run a sewing factory, you’d never have done this’ but I’ve got the best team. Edith Gibson, who runs the sewing team, has got a mindset that’s phenomenal. Between us, we’ve nailed the production and the production flow.”

The beauty of their individuality is that the onesies are all-inclusive – anyone can have one, no matter what their shape or size. One of Kate’s proudest achievements is having worked with The National Autistic Society to create the Sensory Onesie.

“They have Onesie Wednesday, so we’ve always supplied onesies for their team members,” she says. “Sensory issues are a big deal for some people – they cannot bear to wear clothes – so we worked with about 10 families, who came to our factory and told us what they liked and didn’t like, what they really couldn’t bear. We came up with the perfect Sensory Onesie, where the labels go in a gift card and the seams can’t be felt – we actually sew them down. The National Autistic Society get five per cent of every sale.”

To coincide with the 10th anniversary, Kate is launching a new website, which, to her excitement, will have a 3D onesie builder. There’ll also be websites for Germany and the USA – both big customers, along with Australia, New Zealand “and everywhere in between”.

A long-term goal is preserving skills through apprenticeships and work experience – so the company can carry on making the onesies that people want. “We have customers who have been with us from the start and come back to us with lovely messages,” says Kate. “It just keeps you buoyant, it keeps you driving for the next thing.”