LONDON — September is shaping up to be a landmark month for Marks & Spencer, which is returning to the elite FTSE 100 index of the London Stock Exchange on the back of sales and profit growth, and investing further in its beauty business.

Third-party brands are proving to be big money-spinners for the division and now represent 42 percent of total sales at M&S Beauty.

The store said it has been seeing a significant crossover between clothing, home and beauty customers, and next month it will begin stocking more than 30 Estée Lauder fragrances in-store and online. This week the retailer launched Floral Street, the indie fragrance brand owned and run by Michelle Feeney, a former Estée Lauder Cos. executive.

Although Floral Street sells at retailers including Space NK in the U.K.; Mecca in Australia, and Sephora in the U.S., Feeney believes that distribution through M&S will supercharge her brand and take it to a new, national audience.

Floral Street is being distributed through 19 M&S stores, and online. The fragrances include the brand’s bestselling Wonderland Peony, and its latest launch, Sweet Almond Blossom, which was made in collaboration with the Van Gogh Museum in Amsterdam.

Two years ago, Floral Street became the first fragrance partner of the Van Gogh Museum with a scent called Sunflower Pop, inspired by the artist’s “Sunflowers, 1889” painting.

At the time, Feeney had inked a four-year deal across fragrance and scented home products inspired by the work of Van Gogh. Her aim was get audiences around the world talking about “fine art and fine fragrance” in the same breath.

In an interview, Feeney argued that Floral Street and M&S make a good pair; they have a similar democratic spirit, cross-generational appeal and accessible price points.

A 50ml bottle of Floral Street fragrance costs 68 pounds, while a 10ml one is priced at 28 pounds. The discovery set, which costs 18 pounds and features eight 2ml sprays, launched last week on M&S online and Feeney said it’s already a bestseller.

The fragrance will also be added to the M&S Summer Beauty Bag in 2024 with 200,000 samples.

“I love Space NK, and we’ve had the most successful first year with them, but if you want to be a big British brand,” Marks & Spencer is the place to be, said Feeney, adding that her first job was as a Saturday worker at the M&S in Solihull, in the West Midlands of England.

“They’re right across the country — more British consumers see your brand — and the store speaks to quality, value and trust,” she added.

Feeney said the dynamics of masstige beauty consumption in the U.K. shifted once Debenhams, a national store chain with a robust beauty offer and loyalty program, collapsed in late 2020. Boohoo later purchased some of the assets, but the 150 stores shut.

“I am very excited about what Marks & Spencer has done to be a modern distribution channel in the U.K. They have pivoted to bigger store formats, grown their food offering, and created the Sparks [loyalty] card which allows them to reach so many consumers. With Debenhams going out of the marketplace, where do people go for beauty?” she said.

M&S will also be stocking the home fragrance collections, which include plant-based scented candles that are hand-poured in the U.K. and made with natural, paraffin free wax and clean burning unbleached cotton and linen thread wicks.

Feeney noted that M&S wasn’t a part of her brand’s original rollout plan, but it was an opportunity she couldn’t turn down. Feeney said she’s hoping that M&S becomes Floral Street’s biggest U.K. retailer, and she’s expecting the store to generate 20 percent of Floral Street’s U.K. business in the first year.

She said the beauty team members at M&S “look and listen. They know their customers. They’ve [transformed] food and Fashion and now they want to go after beauty in a bigger way, and I also want to be also part of other people’s successes,” Feeney said.

She built Floral Street as a sustainable brand, and believes its values dovetail with those of Marks & Spencer.

From the start she has used vegan, cruelty-free ingredients and packaged her scents in pulp boxes so green they can double as seed trays before biodegrading. There is no excess packaging — such as cellophane wrap — while each refillable glass bottle showcases an original flower mural.

Floral Street is sold in more than 22 countries, and has retail sales of around 15 million pounds equally divided between the U.K., North America and Australia. Home fragrance represents around 20 percent of the business, and the plan is to expand into bath and body.

Feeney said that, depending on the market, sales are in double- or triple-digit growth. She’s headed to the U.S. later this month to give some face time to QVC, one of Floral Street’s biggest distribution channels in the market.