They married in 1950 and eventually settled at Hickory Hill, a sprawling white Georgian mansion in McLean, Virginia, which they had bought from JFK, as Robert embarked on a political career.

Their life together was once described as “organised bedlam”, full of children and animals, including 16 dogs at the same time, a sea lion named Sandy who lived in the family swimming pool, exotic reptiles that lived in the basement and a miniature horse that arrived one Christmas morning in a baby’s playpen. Ethel was pregnant for an astonishing 99 months of her life, giving birth to her 11th child, her daughter Rory, six months after her husband was killed.

Ethel never enjoyed the glamour of her high-profile sister-in-law, Jackie, yet her devotion to her husband helped him to build his confidence: “Everything came so naturally to Jack,” she recalled. “Bobby always had to struggle for it, for everything. And he always thought it was because he was at the bottom of the heap growing up.”

It was often said that Ethel hoped to “out-Kennedy” her mother-in-law, the family matriarch Rose, who, had produced only nine children. In a 1968 Gallup poll, she was named the most admired woman in America. Rose finished second.

A keen athlete, Ethel was once described as running family activities like an Olympic boot camp. When skiing, they took to the mountain early and stayed until the lifts were closing. In summer, she would play several ferocious rounds of tennis in the morning, then take the children out sailing daily at 12.30, cramming up to 15 people into the family’s 26ft sailing boat.

Son Chris recalled being forced, aged 14, to play tennis, with two younger brothers, against journalist and amateur athlete George Plimpton, an accomplished tennis player, in 38-degree midday heat: “At that point in our lives we all hated tennis. We got through the first set and he said, ‘Let’s play another,’ and we all burst out crying.”

He also recalled a sailing trip in rough seas when Sammy Davis Jr was so scared that he went down below. Ethel, always the skipper, refused to go back to shore unless he agreed to sing The Candy Man to the children – “which for a while he refused to do until he realised his life was in the balance. His crying wife convinced him to belt one out for the crowd.”

On another trip, a dean at Brown University who could not swim fell overboard. One of the Kennedy children dived in and dragged him back to the boat but, as he was rather large, it needed several hands to haul him aboard – but not before Ethel Kennedy asked: “Can my children have on-campus housing?”

In his 1978 book, Robert Kennedy and His Times, the historian Arthur M. Schlesinger Jr called the Kennedy mansion “the most spirited social centre in Washington” in the 1960s. “It was hard to resist the raffish, unpredictable, sometimes uncontrollable Kennedy parties,” he wrote.

Hickory Hill was a magnet for the famous and powerful, sometimes at their own risk. Amy Carter, daughter of President Jimmy Carter, was nearly trampled by an elephant at one of Ethel’s pet shows. The Kennedy children, having rigged up a zipwire from the top of Hickory Hill to the swimming pool, charged guests 25 cents to take the daring ride; one taker was the future president George HW Bush. Jackie Kennedy was later reported to have refused to allow children Caroline and John to visit because their cousins were too wild.

“Hickory Hill! They ought to call that place Horror Hill,” Paul Nass, a cook who lasted less than a day at the estate, told The Washington Post. “They should raise pigs out there, they eat so many BLTs.”

When JFK appointed his brother as attorney-general, his sister-in-law quickly emerged as one of the more colourful members of the extended Kennedy clan. At one point Ethel was charged with horse theft – then a hanging offence in Virginia – after she rescued a neighbour’s maltreated horses. She was acquitted.

There were frequent reports about her speeding offences and she made headlines when she crashed her motor scooter while visiting Vatican City. JFK asked her to tone down her parties after press reports of a soiree at which all the members of his cabinet were thrown into the swimming pool.

Ethel indulged her children’s youthful interest in politics, though she never pushed any of them towards a political career. Her daughter Rory recalled how, after she and her brother Douglas saw televised coverage of arrests being made at Washington anti-apartheid protests, they had told their mother they wanted to get arrested in front of the South African embassy. “Mummy, without missing a beat, said, ‘Great, let’s go down there right now.’ She took us down and we got arrested, and she couldn’t have been prouder.”

Ethel Kennedy, trim, smiling, tanned in sleeveless shifts, was always at her husband’s side during campaigns, Congressional hearings and civil rights marches, often with several children in tow, and was credited for bringing him out of his emotional shell. She was his chief comforter when JFK was assassinated and Bobby went through “six months of blackness”.

When her husband was gunned down while delivering a victory speech at the California primary in Los Angeles in 1968, Ethel Kennedy was three months pregnant. She could never discuss his death, explaining in Ethel (2012), her daughter Rory’s documentary, that she coped by getting on with her life and looking after their children, sustained by her strong Roman Catholic faith. “When we lost Bobby, I would wake up in the morning and think, ‘He’s OK. He’s in heaven, and he’s with Jack, and a lot of my brothers and sisters, and my parents.’ So it made it very easy to get through the day thinking he was OK.”

She never considered remarrying. “How could I possibly do that with Bobby looking down from heaven?” she told People magazine in 1991. “That would be adultery.” In 2003, she sold Hickory Hill and moved to Hyannisport, Massachusetts.

Ethel Kennedy raised money for numerous charities later founded the Robert F. Kennedy Center for Justice and Human Rights, though she never liked being asked to share her feelings about the social causes she supported. “All this introspection,” she told her daughter. “I hate it.”

She was awarded a Presidential Medal of Freedom by President Barack Obama in 2014.

Ethel Kennedy is survived by nine of her 11 children; Robert F Kennedy jnr campaigned in the 2024 US presidential election, initially for the Democratic nomination, then as an independent candidate, before withdrawing and endorsing Donald Trump.

The Telegraph, London