Gerard F. Doherty first met John F. Kennedy at the Bunker Hill Day parade in 1946, outside the Doherty home on Charlestown’s Washington Street, where JFK was campaigning in his first congressional run — “this really skinny guy in a tan suit and soft hat,’’ Doherty remembers.

Now, more than 70 years later at age 89, Doherty has penned a book about his experiences as a soldier — and sometimes field general — in the Kennedy political army. “They Were My Friends: Jack, Bob and Ted’’ details some 40 years of campaigns, from Doherty’s own bid for a Charlestown state House seat to Ted Kennedy’s 1962 Senate race to RFK’s 1968 presidential run, with even a little Jimmy Carter 1976 thrown in for good measure.

A lifelong Charlestown resident — save for two years at a sanatorium in Saranac Lake, N.Y., while he recovered from tuberculosis while in college — Gerry Doherty also details his work as a lobbyist and developer, where he made his money. Doherty said he never took a cent for all the work he did for the Kennedys on the campaign trail.

When they offered to pay, Doherty, who along with his wife was making payments on a new sofa, asked his father, who counseled against going on the payroll.

“ ‘They will own you; and if you’re working for them, they can fire you’,’’ came the response, Doherty recalled during an interview last week in his Franklin Street law offices, festooned with Kennedy memorabilia and Charlestown history.

Doherty’s book is a field manual for political operatives, or a delicious history for those interested in the practical arts of securing votes, even though their names aren’t on the ballot. There is little lyrical language, but an enjoyable number of detailed anecdotes.

“He was quiet, but he had the guts of a burglar,’’ said Charles U. Daly, who was an aide to President Kennedy and later director of the presidential library of the museum, describing Doherty’s political style.

Doherty’s benefactors Jack, Bob, and Ted — or, one might argue, his beneficiaries — don’t come in for a great deal of scrutiny in the memoir. There’s no nod to the questionable off-books deals in the 1960 presidential campaign, no mention of Chappaquiddick, or any discussion of the various transgressions of subsequent generations of Kennedys, even if Doherty has been around almost from the beginning.

Kennedys don’t cry, the saying goes, and Kennedy hands certainly don’t spill the family secrets.

But Doherty, who may be the last surviving political professional who worked campaigns for all three Kennedys — not to mention Carter, and as an adviser to late mayor Thomas M. Menino — has plenty of stories to tell.

He was with Ted the night President Lyndon Johnson said he wouldn’t seek reelection, and he was alongside Bobby the night he won the Indiana presidential primary. He accompanied Carter’s mother, Lillian, to the Vatican for the funeral of Pope John Paul I.

He first ran for office — a former Charlestown sandlot football hero, Harvard grad, and tuberculosis survivor — as a state rep candidate in 1954, losing narrowly. He won two years later, seizing on a tactic seemingly ripped from the Google Earth era: circulating 2,200 photos of the homes of about 70 percent of the district’s voters — with written reminders that Doherty had knocked their doors.

Doherty still lives in Charlestown, in the same house where he grew up. Campaigning techniques, though, have changed.

In some respects, Doherty anticipated the modern-day methods of organizing volunteers and fund-raisers via Facebook and e-mail. Doherty used observation and street-smarts.

In Indiana in 1968, in what he concedes was a bit of a “Machiavellian’’ move during a desperate hunt for signatures to land Bobby Kennedy on the primary ballot, Doherty by happenstance spotted a few high school kids wearing “Crispus Attucks’’ sweat shirts.

Attucks was, he learned, a nearby Indianapolis high school named for the first person killed in the Boston Massacre and, later, a symbol of the antislavery movement. Doherty called the school’s principal and, noting the Massachusetts tie, suggested the school band could lead the parade the next week when RFK formally filed his signatures.

Then, he called the principal back and said he would need to cancel the band’s performance because the campaign would likely fall short of the signature requirement. When the principal expressed disappointment, Doherty suggested that maybe the students could flock to the city’s black churches and perhaps assist with the signature-collection effort.

Kennedy got the signatures.

Doherty also writes about visiting Ted Kennedy during his months in the hospital after his 1964 plane crash. Kennedy, from a famously wealthy family, peppered him with questions about how a working-class guy would pay for such health care.

Doherty explained the financial sacrifices, and Kennedy asked for more information and about how other countries set up their health care systems.

It was, Doherty said, the seeds of Kennedy’s nearly career-long quest for the United States to adopt universal health care coverage, for which he cast a key vote in 2009 while dying of cancer.

There are, to put it mildly, plenty of Kennedy books. But Doherty, who sat at a conference table nattily attired with a tie-clip reading “Kennedy 1964,’’ said he had the idea to write his firsthand account after Ted Kennedy died.

While his friend lay in state, Doherty met mourners. “Invariably, people would ask, ‘How did you meet him?’ and for more stories.’’

Doherty realized he had a pretty good tale to tell about what he calls in the book “a friendship that changed my life.’’

Doherty is set to headline an event about the book on Oct. 22 at the JFK Library, which organizers said has already been moved twice to larger spaces due to accommodate interest.

Daly, who recalled seeking Doherty’s counsel while leading the library, said Thursday he had not yet read the book, but would.

“If it’s half as good as he is,’’ Daly said, “he’ll get a Pulitzer Prize.’’

Jim O’Sullivan can be reached at jim.osullivan@globe.com. Follow him on Twitter at @JOSreports.