Catherine Holmes’s life has been full of incongruities.

Her father, Joseph Hamilton, had wanted to be a physician but ended up as a police lieutenant. Her mother, Evelyn, was a strict disciplinarian but also full of love.

As a child, she memorized the names of all 21 counties of her native New Jersey but missed being the local champion speller when she inserted “e” instead of the second “a” in “allegiance” during a hotly contested spelling bee.

She could have been a lawyer or a teacher but wound up instead as a realtor, one whom many call the queen of the Upper West Side.

She sold an apartment for a man named Thomas Holmes and soon became his spouse.

She attended a rugby game to please her husband, and was eventually elected to the board of the Old Blue Rugby Foundation, as its only female board member.

She teamed up with her husband in running a restaurant and savored its success for two years before realizing how tough a business it was to sustain month after month.

She wanted to sign on to an industry that was less stressful and found herself in the world of New York real estate.

“Well, what can I say – it’s been fun,” Ms. Holmes said.

If fun means a 24/7 schedule, then Ms. Holmes, director of residential sales at Barak Realty, a boutique residential real estate firm, is indeed having a good time.

If fun means memorizing the names, addresses, and floor plans of hundreds of buildings on the Upper West Side – defined as the zone west of Central Park from 59th Street to 120th Street – then Ms. Holmes is having a splendid time.

Her fun has resulted in the building of a solid reputation in the business, where sniping is more the norm than the exception.

For Manhattan’s Upper West Side, however, Ms. Holmes has nothing but praise. “The Upper West Side offers something for everyone,” she said. “The buildings are so beautiful, especially in contrast to the post-war white cookie-cutter buildings of the Upper East Side. The buildings have so much character.”

Part of the reason they have such character is that many of them are very old indeed. Some of the Upper West Side’s brownstones date to the 1860s. Many buildings were raised in the 1920s, when there was a surge in construction as New York City’s population increased, as did its affluence. And a large number of these edifices contain classic six-, seven-, and eight-room apartments.There’s also a proliferation of five-room Edwardian apartments.

A one-bedroom condominium of about 800 square feet is easily $700,000. A slightly larger apartment? That would set you back by another $100,000 or $200,000.

So, the reporter asked, who can afford to live on the Upper West Side nowadays?

Ms. Holmes smiled.

“Ah,” she said.”The Upper East Side has yet to catch up with the Upper West Side. We have a lot more family-oriented neighborhoods. But I’ll admit – it’s hard getting into many of these buildings, and it’s hard getting out.”

Was it hard for her to leave her previous job as vice president at Prudential Douglas Elliman, where she was a top-ranked broker?

“Yes, of course,” Ms. Holmes said. “Barak kept after me for more than a year.”

“Barak” is Barak Dunayer, president of Central Place Realty, and he had long wanted to make his mark on the New York real estate scene, which is dominated by well-established mega-companies such as Prudential Douglas Elliman.

“What will it take for us to get you over?” Mr. Dunayer once asked Ms. Holmes, the mother of two children, Allyson Hamilton Cheah and Tommy Holmes.

“A stick of dynamite,” she said.

Mr. Dunayer then employed a far more persuasive method: He convinced Ms. Holmes she had better prospects of shining at a small boutique firm such as his.

“Top producers at big-brand agencies such as Prudential Douglas Elliman and the Corcoran Group are finding more recognition, better financial arrangements, and more opportunity for creative brokering in boutique agencies,” Mr. Dunayer said to Ms. Holmes.

For Ms. Holmes, a boutique agency meant the opportunity for more of a managerial role, one in which she took on the task of training other brokers and developing a sharper marketing strategy.

“I advise my colleagues to always want to get the deal done,” she said. “That means persistence, persistence, persistence. It means keeping a positive attitude and listening carefully to your customers.”

Would she consider retiring?

Ms. Holmes looked stricken.

“Retire?”she said.”Retire? I’m a baby boomer. Baby boomers never retire.”