Shamrock Social Club is the place to get inked in Hollywood - as Cate Blanchett has shown

The slogan of the Shamrock Social Club, a tattoo parlour on the Sunset Strip in West Hollywood, is "a place where the elite and the underworld meet".

The store may be frequented by members of Los Angeles's famous street gangs, but it is also the tattoo parlour of preference for several major Hollywood celebrities. And on Monday, the day after the Academy Awards, its clientele was classed up by the arrival of the Best Actress winner, Cate Blanchett, and her fellow nominee Amy Adams.

The two stars, who were photographed hugging one another inside the parlour, have never worked together, but both were close to Philip Seymour Hoffman, and it has been speculated that Blanchett's tattoo is a tribute to the late actor. The 44-year-old Australian exited the Shamrock with a length of black tape around her wrist, concealing the design. Both women were accompanied by their other halves, and Adams's fiancé, Darren Le Gallo, also had a tattoo done.

The Shamrock has not revealed Blanchett's choice of tattoo, and its proprietor, Mark Mahoney, is known not only as a "legendary" artist, but also as the soul of discretion when it comes to his celebrity regulars. His earliest clients included punk rockers such as Sid Vicious of the Sex Pistols. Later, he inked hip-hop rivals Tupac Shakur and the Notorious BIG. He tattooed a sparrow on Johnny Depp's arm, after the actor played Captain Jack Sparrow in Pirates of the Caribbean.

The Shamrock is three miles from the Dolby Theatre, where the Academy Awards were held. During the past decade, it has served a parade of Hollywood personalities, among them Blanchett's fellow Oscar winners Jared Leto and Brad Pitt. Its artists have even inked several celebrity Brits on a pilgrimage to the Strip: Fearne Cotton, Russell Brand, David Beckham, Harry Styles, Adele.

As if adorning movie stars were not enough, Mahoney recently began a film career of his own, and will shortly appear in a cameo role in the New York crime drama Blood Ties.

Mahoney – mid-50s, slick of hair and pointy of shoe – began his career as a punk tattoo artist in Boston in 1977, at a time when the practice had been banned throughout his native state of Massachusetts due to an outbreak of hepatitis – supposedly traced to insanitary tattoo parlours. He moved to New York and later Los Angeles, where he developed his signature monochrome style, based on the body art of Latino prison-gang members.

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Although Mahoney opened a tattoo parlour of his own in 1985, according to a recent profile in the Los Angeles Times, he was forced to give it up after four years because he was in the grip of heroin addiction. He struggled through rehab and returned to tattoo art, against the advice of counsellors, who told him the work would send him spiralling into the same bad habits.

Mahoney proved them wrong, marrying and having two children before, in 2002, he opened the Shamrock Social Club on Sunset Strip, just yards from the Viper Room club, where River Phoenix died of an overdose in 1993. The establishment is called a "social club" because customers are encouraged to mingle and to play pool at the table in the waiting area.

The studio is decorated with images of three-leaf clovers and images of the Virgin Mary, relics of Mahoney's Catholic Irish upbringing. Whether you're from the underworld or the elite, a custom tattoo costs $500 (£300) for a single sitting, and into the thousands for more complex designs. Clients who want their bodies inked by the boss will wait as long as six months for an appointment with Mahoney, who typically works the late shift, from 5.30pm to 1am.

"I wanted a place where people would feel welcome," Mahoney has said. "People remember the nights they got tattooed… I wanted to make that as memorable and as nice an experience as it can be."

When it comes to celebrities such as Cate Blanchett and Amy Adams, it doesn't appear like they'll be forgetting their experiences in a hurry.