President Obama and British Prime Minister David Cameron hold a news conference during the Group of Seven summit in Brussels in June. (Saul Loeb /Agence France-Presse via Getty Images)

In an interview with the Daily Mail published this weekend, British Prime Minister David Cameron revealed the depths of his relationship with President Obama.

"Yes, he sometimes calls me 'Bro,'" Cameron told the British newspaper, adding that the U.S. president also phones him.

At first glance, Cameron's comments seem deeply personal: an acknowledgement that statesmen have personal relationships, too. But it's also a very political message. Just months away from an election, Cameron was invoking the storied "special relationship" that is said to exist between Britain and the United States and saying that, yes, it was still strong.

The relationship was first noted by Winston Churchill during a 1946 tour of universities. Speaking at Westminster College in Missouri, he spoke of the need for a "fraternal association of the English-speaking peoples" in opposition to the Soviet threat. "This means a special relationship between the British Commonwealth and Empire and the United States," the British leader said.

But Cameron might want to be careful. Since then, the relationship has gone through a variety of chapters, with many ups and downs.

The seduction

President Franklin D. Roosevelt, left, and Prime Minister Winston Churchill aboard the HMS Prince of Wales on Aug. 14, 1941, working on the principles of fair dealing that became the Atlantic Charter. (Associated Press)

Even before his 1946 speech, Churchill made the "special relationship" a key aspect of his foreign policy. During World War II, he used the relationship to help persuade Franklin D. Roosevelt to lead America into the war. "No lover ever studied every whim of his mistress as I did those of President Roosevelt," he said in 1946. Churchill later enjoyed good relationships with Harry Truman and Dwight D. Eisenhower.

The breakup

One of the most prominent victims of the relationship was Anthony Eden, who succeeded Churchill as prime minister in 1955 and took a more critical view of the United States' geopolitical ambitions. Eden resigned in 1957, after the failure of the Anglo-French military intervention in the Suez crisis, which the United States refused to support as Eisenhower was concerned about a Soviet response.

Unlikely friendships

President John F. Kennedy walks British Prime Minister Harold Macmillan to his car on April 29, 1962, at the White House. (William J. Smith/Associated Press)

Harold Macmillan, who served as British prime minister from 1957 to 1963, enjoyed a surprisingly close relationship with John F. Kennedy during a time of Cold War tension. "I feel at home with him because I can share my loneliness with him," Kennedy told a British newspaper at the time. "The others are all foreigners to me."

The refusal

Harold Wilson's decision not to send British troops to the Vietnam War (despite some support for the war within his party) led to a strained relationship with Lyndon B. Johnson. When Wilson asked to travel to Washington in 1965, apparently hoping to play the role of mediator, he was rebuffed by the president. "Why don’t you run Malaysia and let me run Vietnam?" Johnson told Wilson.

The 'natural' relationship

Edward Heath sought to put less emphasis on the relationship with America and instead looked toward Britain's burgeoning ties with Europe. He spoke of the British-U.S. relationship being "natural" rather than "special," which apparently prompted the ire of Richard Nixon.

The frustrated 'power couple'

Ronald Reagan and Margaret Thatcher wave after their arrival in Camp David in December 1984. (Archives UPI via AFP/Getty Images)

Margaret Thatcher and Ronald Reagan are often taken as the ideal for the "special relationship." The pair's economic and geopolitical outlooks were remarkably similar, but the relationship wasn't always perfect. Reagan had to personally apologize to the British prime minister for the U.S. invasion of Grenada in 1983, the same year that Thatcher called Reagan's decision to withdraw troops from Lebanon "a naive failure."

The lapdog

President George W. Bush talks with British Prime Minister Tony Blair, right, during a private luncheon in St. Petersburg on July 17, 2006.  (Pool photo via AP/AP Television Newsl)

Tony Blair was an enthusiastic supporter of the special relationship, pushing for a deep British involvement in U.S.-led wars in Afghanistan and Iraq, leading the British press and public to label him a "lapdog" for George W. Bush. Things were made worse in 2006 when Bush was recorded privately greeting the prime minister with what was described as "Yo, Blair!" (although others argued that the U.S. president was actually saying "Yeah, Blair"), which was taken as a sign of America's condescending relationship with Britain.

The bromance

Since David Cameron came to power in 2010, his relationship with Obama seemed to largely revolve around photo opportunities, be they table tennis tournaments, awkward phone calls or selfies. At times the relationship has appeared genuinely close (in part because of shared concerns over the Islamic State militant group and Russia), but Cameron, facing an election later this year, may have some reason for concern: As Arwa Mahdawi notes at the Guardian, calling someone a "bro" isn't always a good thing.