Hart began his career as a reporter in Central Africa, on the Nyasaland Times, and served as a war correspondent in Vietnam. He tells of having been the first Western correspondent to reach the banks of the Suez Canal with the Israeli army in 1967. He also tells of having been friendly with both Golda Meir and Yasser Arafat at roughly the same time and having been on friendly term with such leaders as Saudi Arabia's King Faisal, Jordan's King Hussein, and both Egyptian Presidents Nasser and Sadat.

Hart says he was told by his editor Geoffrey Cox early in his career, "Never forget that leaders are the most lonely people in the world because they are surrounded by sycophants who only tell them what they want to hear. They, the leaders, are crying out for honest conversation." Inspired by this advice, he says, he held "private one-on-one conversations over the years with leaders on both sides of the Arab-Israeli connection, giving him a rare insight into the truth of what they really believed and feared as opposed to what they said in public for propaganda and myth-sustaining purposes."

In 1973 Hart addressed global poverty with a two-hour film titled "Five Minutes to Midnight." Its world premiere was hosted by Secretary General Kurt Waldheim at the opening of the 7th Special session of the UN General Assembly that had been called to discuss for a new world economic order.

Hart was involved in the failed attempt by the late Shah of Iran to go into exile in the UK after he was deposed from power. On February 9, 1979, as a freelance journalist close to the shah, Hart contacted Downing Street to say the deposed royal was interested in living full-time at his lavish estate in Surrey, southwest of London.

Hart also tells of having been the unofficial linkman in a secret exploratory dialogue between Arafat and Shimon Peres in 1980.

Hart has never been a member of any political party or group. When asked what drives him he has said, "I have three children, and, when the world falls apart, I want to be able to look them in the eye and say, "Don't blame me. I tried." [press release, April 28, 2010]

Israel

Hart is a sharp critic of the state of Israel, writing in 2007 that:

The colonial enterprise that Zionism is has corrupted everything it touched, beginning with the United Nations and including the mainstream media, what passes for democracy in the Western world (America especially) and Judaism itself.

In a letter to British Conservative Party leader David Cameron in August 2007, Hart wrote that "the Zionist state, which came into being as a consequence of Zionism terrorism and ethnic cleansing, had no right to exist and, more to the point, could have no right to exist unless ... it was recognised and legitimized by those who were dispossessed of their land and their rights during the creation of the Zionist state. In international law only the Palestinians could give Israel the legitimacy it craved. And that legitimacy was the only thing the Zionists could not and cannot take from the Palestinians by force." He also stated that the "Jews who went to Palestine in answer to Zionism’s call had no biological connection to the ancient Hebrews. The incoming Zionist Jews were mainly foreign nationals of many lands... The notion that there are two entire peoples with an equally valid claim to the same land is an historical nonsense." Hart has also suggested that Israel might attempt to trigger a war between the United States and Iran using a stolen American nuclear weapon and that Israel will expel all of the Palestinians living in the West Bank and Gaza strip as soon as the opportunity presents itself

9/11 Truth movement

In May 2010, Hart stated on various media, including the Kevin Barrett Show, that consultants close one the world’s most prominent construction company assured him that “The twin towers were brought down by a controlled ground explosion, not the planes.” Hart also speculated that the planes had been fitted with transponders and that Israeli Mossad agents were guiding them in to the towers. Regarding the purpose of the 9/11 attacks, Hart stated that: “My guess is that at an early point they said to the bad guys in the CIA — hey this operation’s running what do we do, and the zionists and the neo-cons said let’s use it.”

Hart is the author of several books including a 1984 biography of Yasser Arafat,Terrorism or Freedom Fighters: Yasser Arafat and the PLO. More recently he has completed the trilogy Zionism: The Real Enemy of the Jews In an article discussing his book, Hart stated that "until enough Americans are made aware of the truth of history, no American president will have the space to break the Zionist lobby’s stranglehold on Congress."