Karol Solomons, 80, is dressed in a rose gold metallic top with matching shirt, her trainers, Converse style lace-ups, glisten in the same shade, white slimfit trousers rest just above them, showing an on-trend flash of ankle. She is no ordinary grandma.

Still at work in her boutique, Harpers in Edgware, north-west London, the store she opened with her husband Sydney, 45 years ago, Solomons is organising stock for its anniversary party today.

“I buy what I like,” she says as I browse the rails of maxi dresses, embroidered jeans, and swimwear from celebrity-favourite brands such as Melissa Odabash.

“I never buy anything if I don’t like it. Everything is virtually to my taste.”

She has been dressing the Jewish community for simchas for 45 years and her cash desk is adorned with thank-you cards and presents.

Her oldest customer is 86 and the youngest 17, a girl who came in with her mother and grandmother last weekend.

“We send them flowers when they get married, we go to their shivas, we check in on them when they are unwell. It is a part of the community.

“Look at these people who have thanked me for help, what shop gets that? It is amazing.”

Solomons has compiled collages of pictures sent in by customers, including one customer in a Harpers dress, standing next to Prince Charles.

“The ‘Harpers woman’ comes in every day, sometimes just for a coffee and a chat.” Some like to pop in with their pets. “We have a dog bowl out the back for them,” she says.

“We are part of their everyday lives; it is not like shopping anywhere else.

“We have one customer who changes her lipstick for each outfit that she tries on. Then we have three sisters- in-law who come in and we have to be careful not to sell them the same thing.

“One woman only wanted to try on size 25 jeans. She would never buy them, but she’d be here for over an hour. In the end we had to hide them when she came in.”

It is not just her customers that are loyal. The store has a unusually low staff turnover.

Sales assistant Vivienne Wright has worked at Harpers for 32 years.

She says: “People call us a drug shop, they feel low and they come in here and get their fix.

“I have one customer who comes in and gets exactly what I’m wearing. It doesn’t matter what it is, she has to have it.”

When Solomons opened the store — the name inspired by Harper’s Bazaar magazine — she was married with two children and working part time in the West End in fashion PR.

Keen to spend more time with her family, she set up shop nearer home.

She never intended to have a career in fashion.“I thought fashion was trivial. I studied dietetics and went to university and I wanted to be serious.”

How wrong she was. “I love it,” she beams.

Harpers is very much a family business. Solomons works alongside her daughters, Lucy, a former teacher and Katie, a fashion agent in Paris, who helps buy products for the store.

“I used to do the buying on my own but now they don’t let me.

“Katie is more high fashion, Lucy is more practical and I know what sells. We are a nightmare to please, but it must work because we are still here 45 years later.”

Despite the surprisingly modern stock for a boutique that I had (wrongly) assumed only served the more mature customer, there are elements of her business Solomons still likes to keep old-school.

“We still manage our stock through a book. I can see who bought what, when, and how many items we still have. And doing the tickets at the end of the day is my highlight.”

Harpers has survived the threat of online shopping that has crushed so many other boutiques.

Lucy says: “We tried going online but it didn’t work for us because we have such a swift turnaround of stock.

“By the time we’d uploaded everything, we’ve probably sold out.

“We make about 50 phone calls to our customers when we get new stock saying this has come in and you will love it.

“And we can have sold out by the end of the day.”

Her mother says the needs of Jewish women have changed since the layered look of the 1970s and the power dressing of the 1980s, but one thing remains the same.

“It all comes back round again. Today, women are much more individual and there is more competition out there so the buying we do has to be really unique. It has to be different to what they had before.

“I used to buy jackets and trousers in every colour and now it is so much more difficult.”

As for taking a rest and letting her daughters take over?

“No chance,” she says, “people my age might hobble round with their sticks, but not me. I get up every day to come to work and I love it.”