Sarah Campbell has been working from home since long before a certain highly contagious virus made it the norm. The octogenarian print designer’s studio is in the second bedroom of her rented flat in Gipsy Hill, but handpainted scraps, doodled paper and piles of fat quarters — which patchwork hobbyists can’t get enough of — spill out across every surface of the living room. “I’m not a good throw-away-er. The trouble is, it all comes in handy,” she chuckles.

Of the sofas laden with works in progress she explains: “Things move around a lot — in piles! The thing is, I’m always between things; last week I was teaching handpainted fabrics at the Fashion and Textile Museum and just before that, I was in West Yorkshire making some little films about how to paint things, so I’m always unpacking, packing, unpacking…”

Campbell’s work— and that of her late sister and collaborator, Susan Collier — is currently the subject of an exhibition at the Fashion and Textile Museum in Bermondsey. Paint! Pattern! Print! opened in spring and runs until mid-September.

The pair were prolific, working on designs for textiles, homewares, fashion for brands such as Liberty and Habitat alongside licensing agreements with brands in America. Neither were formally trained: Collier started out by assisting textile designer Pat Albeck and joined Liberty as a design and colour consultant in 1971. Campbell, eight years her junior, shared her gift for drawing and was asked to help out; she has been working freelance ever since. “All I’ve done all my life is paint patterns, and I have never had a proper job inside an institution or anything like that,” she says.

The exhibition celebrates the breadth of their creativity and Campbell was almost the sole lender of what is on display. Perhaps unbelievably, her home’s inventory has actually thinned out as a result of it. “I just unpinned everything that was on my studio wall,” she says. The sisters worked together for 50 years and for a short spell had a boutique off Bond Street. Susan died of cancer aged 72 in 2011 and their shared archive is kept in St Leonards-on-Sea. “I am very pleased that our work is being acknowledged. It’s covered such an enormous span of time,” she says.

Campbell has lived south of the river since leaving home aged 18; for a long time she and Susan both lived in Clapham Old Town and shared a studio nearby. She later moved to an “extraordinary bungalow” in Tulse Hill before living in a flat close to her current one for several years. She has rented in this Austin Vernon-designed block on the Dulwich Estate for 13 years. “What’s very nice about all these flats is they’re more or less the same — it’s very egalitarian, so everybody knows where they are,” she says.

The open-plan living area is generously-sized and flanked by large windows. “I love being neighbours with the squirrels and magpies and seeing the leaves,” she says. Atop some open shelving made by her nephew are the ceramics she designed for the American retailer West Elm. The dining table has inevitably become a work table, but it’s a family heirloom which her parents had made by an architect friend when they were a young couple living in Manchester. There is also a useful porch for coats and shoes (but Campbell’s, naturally, is chock-full with books and yet more creative inventory).

Gen Z renters disgruntled by the London property market could do well to take heed of Campbell’s get-on-with-it approach. “It’s always worth making somewhere homely — it would be horrible to live somewhere where you didn’t have a semblance of home. Even with just a lovely postcard on the mantelpiece, you can build up from that,” says Campbell. She has painted the odd wall but learned to live with the venetian blinds and light fixtures she inherited. Unsurprisingly, she thinks fabrics are key to personalising a place: “They’re so portable and so immediately lovely. People have very strong attachments to fabric.” In her bedroom, she has a cheery set which she handpainted.

But not all touches have to be for show: Campbell has strips of paper with lacy decoupage stuck along cabinet shelves. “The funny thing is, the shelves are hidden in a cupboard; so you can’t see them except when I open the door, but that makes me feel homey.” Dotted around are pieces by Campbell (the hand-painted, papier-mâché cats and dogs are £20 each from sarahcampbelldesigns.com) and fellow creative friends; an unusual lightbox above the mantel was made by ceramic artist Stephenie Bergman, a school friend.

In the kitchen, colourful mugs by potter David Garland adorn a freestanding shelving unit. “It means that I think about the people a lot as I use them,” says Campbell with a smile. “It’s a collection of my life, really,” she muses, laughing at how the modern parlance for arranging possessions has been coined ‘‘curation’. “It’s an extraordinarily pretentious word in my terms, because it sounds partly like you live in a museum, which isn’t great. But I know it’s much more widely used now.”

The creative celebrated her 80th birthday in February and shows no sign of slowing down. “There are lots of people older than me working — Zandra [Rhodes] and Kaffe [Fassett], are 85 and 88,” she says. “They’re all creative people — doing things with their hands and inventing. That’s a great way to live and I think if you can, you must do it.”

A “good” day starts with a 25-minute session of tai chi with her neighbour over the road, followed by some email admin. “I always make a to-do list the night before so that I sleep on it and know what I’m going to do,” she explains. Then there are workshops to plan and bags to paint. She gets around largely by driving but cherishes the interactions with strangers on trains and buses. “I love to hear the stories about what people have got [with them] or where they’re going.” She also finds travelling “very good for thinking.”

What she dreams of getting her teeth stuck into next is a collection of furnishing fabrics printed in the UK. “A small range — just a handful of designs and colourways on a cotton or a linen.” Whoever is reading this and in a position to make that happen: now is your moment to strike.

Paint! Pattern! Print! is on at the Fashion & Textile Museum, Bermondsey Street, SE1, until September 13