Bartender Kevin A. Armitage was “the life and soul’’ of The Littlest Bar in Boston, where he expertly poured pints of Guinness and filled the sound system with his own extensive collection of U2 recordings, his boss said.

The 46-year-old native of Galway, Ireland, who came to Boston at 19 and worked at several Boston pubs over the years, was found dead Friday morning at his home in Jamaica Plain.

The family does not know the cause of death but believes he might have suffered a heart attack, said his younger brother, Rory, who also emigrated from Ireland and lives in Boston.

Frank Delaney, co-owner of The Littlest Bar in the Financial District, said he knew something was terribly wrong when Mr. Armitage did not show up for work Thursday night. He never missed work, and was he never even late.

“He had pride in his job, pride in what he was doing,’’ Delaney said yesterday.

“He was a man of his word. When he said he was there, he was there.’’

Mr. Armitage’s sudden death sent shockwaves of grief through the Irish community in Boston during preparations for today’s annual St. Patrick’s Day Parade in South Boston.

“Kevin was as healthy a guy as anyone ever knew,’’ said his brother.

Mr. Armitage and his brother had returned to Boston Tuesday after a weekend in San Francisco to celebrate the impending birth of Rory Armitage’s first child.

“It was to be my last hurrah and it ended up being his last hurrah,’’ said the brother, who found the body.

Mr. Armitage’s brother said said he has been overwhelmed with condolences from around the world.

My brother “was known for his laughter, his love of tennis, his love of Manchester United, and his love of his friends and the people around him,’’ he said.

Mr. Armitage was a career bartender. His resume included work at Flannery O’Brien’s in Mission Hill, Phoenix Landing in Central Square, Cambridge, and the Crossroads Irish Pub on Beacon Street.

He began working for The Littlest Bar when it reopened on Broad Street two years ago after more than 60 years at Downtown Crossing.

His expertise in pouring Guinness recently earned The Littlest Bar a special award. “I told him no one deserves to take that but you,’’ Delaney said.

“He had that attention to detail, everything had to be just perfect.’’

Bar regulars also appreciated Mr. Armitage’s easygoing personality and friendly nature.

“He just had a way about him where everybody could talk to him — that classic bartender thing you don’t think is real but he was the real deal,’’ said his longtime friend John McDermott. “Everyone was his friend.’’

When he wanted to unwind, Mr. Armitage could usually be found at the Brendan Behan Pub in his neighborhood. In the summer, he enjoyed taking boats out on Jamaica Pond.

As a boy in Ireland, he enjoyed spending time with his grandfather on the River Shannon.

His 1987 marriage to Phyllis Jean Beatty ended in divorce in 1990.

In addition to his love of sports and animals, Mr. Armitage was a big fan of U2. Friends noted he resembled Bono when he wore his favorite sunglasses and didn’t shave for a few days.

In addition to his brother, Mr. Armitage leaves his parents, John and Joan of Galway.

A service will be held from 5 to 8 p.m. Tuesday at the Mann and Rodgers Funeral Home in Jamaica Plain. Burial will be private.

© Copyright 2010 Globe Newspaper Company.