ROCKPORT — Find an underserved niche and dominate it.

That’s usually a sound formula for retail or wholesale business success. But for the family that runs Posies, a maker of frilly, Victorian-era style dresses for young girls, it was love — and a small fit of hate — that led to an obscure but lucrative corner of the apparel business.

The family is Angela West and her parents, John and Robin Doncaster. John is from England, Robin, from Australia. They met in Texas, which is where Angela grew up. Even as a child, Angela was drawn to the Victorian age. On a visit to her father’s native country, she remembers buying an antique christening gown.

These sorts of gowns are heirlooms. “It’s supposed to be handed down for generations,” she said.

When Angela’s daughter, Amelia, was old enough to wear a dress, the comparable wear available in the United States just didn’t cut it. “It was all horrible,” she said. Instead of using silk, satin or cotton, the gowns were made of polyester, which fails in the heirloom category because it turns yellow with age.

So West designed and hand-sewed a dress for Amelia that fit the bill. About the same time, Robin Doncaster made a dress for her then 1-year-old granddaughter. But Amelia hated it — “She screamed,” John Doncaster remembered — so the Doncasters decided to sell the dress in their antique shop, The Rockport Mercantile. The dress sold five minutes after it was displayed, John said.

“It was out of that the business of making dresses started,” he said. By the end of the year, a third of the store’s sales were dresses. “We decided to get serious,” he said.

A Posies dress shop was opened in Camden in 1991, but when the wholesale market began to develop, it became a distraction, John Doncaster said, and it eventually was closed. Today, the company operates from a rambling commercial building on Route 90 in Rockport.

The family soon discovered a market for christening wear — fancy, frilly little gowns in which an infant would be baptized, an important ceremony in many religious traditions that is celebrated with family get-togethers.

With West’s Victorian-inspired design sense, the Posies gowns were a hit. Soon after, the business began making First Communion dresses, “which we discovered by accident after going awhile,” John Doncaster said. Roman Catholics and some other denominations mark the introduction of the sacrament of Communion with a church ceremony when children are about 12. It is a big event in a family’s religious life, for which many parents will buy an expensive, finely made dress.

“Little girls should look like little girls as long as we can keep them that way,” West said. Her interest in the Victorian era is not a marketing ploy, she explained, but a passion. The fanciful designs of that time in clothing, architecture and art appeal to the romantic is all of us, she said. The success of the Posies line may bear out her theory.

The business sells about 30,000 units a year and has $2.5 million a year in revenue.

Each year, the christening line includes 20 to 30 gowns for girls and boys. The First Communion line includes 10 dresses.

Recently, Posies expanded into wedding wear, producing dresses for flower girls. The retail prices for the dresses are “pretty exclusive,” in the $160-$190 range, West said. Even so, sales are growing steadily. From November 1998 to March 1 of this year, sales grew by 35 percent, the company says.

For the christening wear, at least, West understands the reasons people might splurge for a top-quality gown. “If you spend all that time having a baby, you’re not going to settle,” she said. Customers are beginning to ask, “When are you going to do wedding gowns?” West said.

“We sell all over the country,” said John Doncaster. With ethnic religious traditions strong in the New York-New Jersey area, Posies does well there, he said. An office in Dallas serves the Southwest, and sales representatives work from Atlanta and Los Angeles.

Many small children’s wear boutiques carry the Posies line, but so do big-name retailers such as Neiman-Marcus, Nordstrom, Bloomingdale’s and, in England, House of Frasier.

In Maine, Porteous in Bangor and The Golden Giraffe in Portland sell Posies apparel.

The business advertises in magazines such as Martha Stewart Living, Town and Country, and Elegant Bride. Ads include an 800 number that readers can call to find a shop close by.

In Rockport, Posies employs 16 to 20 people. Samples of the year’s new lines are produced there for salespeople to show store owners. Two independent contractors in Maine do sewing work.

“I’m looking for additional jobbers around the state,” West said. A factory in New Jersey also does some work for Posies. But West praised her adopted home state.

“Maine has been a wonderful place to grow a business,” she said, citing work ethic, esprit de corps and loyalty among her employees.

The Posies line and name are so successful they are spawning copycats, West said, companies that mimic her designs, but, she says, not her quality. “By the time they copy me, I’m already doing something new,” she said.

Next up is a Posies line of jewelry, and even a Posies doll, with a matching dress for the little girl who owns it.