How secret was the US and British involvement in the 1953 Iranian coup d'état?

Question

A professor mentioned to me that one of the reason that conspiracy theories are popular in Iran (and Middle East in general) was that actual conspiracies involving Western powers against Muslim countries did happen. One such example was the 1953 Iranian coup d'état which overthrew and imprisoned Iran's elected Mosaddegh government. This effectively ended democracy in Iran and replaced it with a strong monarchical rule of Mohammed Reza Pahlavi.

It was orchestrated and planned by the UK and the US. According to Wikipedia, only long after this did these countries' intelligence agencies formally acknowledge their roles.

In August 2013, 60 years after, the American Central Intelligence Agency (CIA) admitted that it was involved in both the planning and the execution of the coup, including the bribing of Iranian politicians, security and army high-ranking officials, as well as pro-coup propaganda. The CIA is quoted acknowledging the coup was carried out "under CIA direction" and "as an act of U.S. foreign policy, conceived and approved at the highest levels of government.

and

Classified documents show that British intelligence officials played a pivotal role in initiating and planning the coup ...

My question was, how secret or well-known were these countries' involvement in this role? Did the general public (in Iran and in the West) know about this? Or did only "conspiracy theorists" believe that the US and the UK did this, initially?

Answer 1

Since we need an older source, rather than a current source, I will quote The Seven Sisters (1975) by Anthony Sampson, which contains an entire chapter on the affair.

As for Dr. Mossadeq, his role in history is still disputed. Among old Iranians, he is now still an embarrassing phenomenon, who bankrupted his country and looked foolish to the world; and the Shah, who had to leave the country because of him, prefers not to hear the name of "that fellow." But to most younger Iranians, he is a kind of Iranian national hero, because he first asserted Iranian nationalism against the companies and the British. -- p. 163

This supports the claim that there was a significant awareness of the coup in Iran during the seventies and the fall of Mossadeq was attributed to the fight with the West over oil.

The book identifies several Western motive forces:

Behind the scenes there were mysterious forces at work in Iran, who were waiting for their moment. Early in the crisis, British secret agents had reported to London that there were many anti-Mossadeq elements in Iran who with encouragement, including cash, from Britain, could help bring Mossadeq down. The Foreign Secretary, Anthony Eden, however, would not sanction a coup and the project was passed on to the CIA in Washington, who were in turn hesitant to act without British support. Eventually the plan was sanctioned, not by Eden, but by Churchill, who happened to be in temporary command of the Foreign Office during Eden's illness in April 1953. The conspirators were duly assisted, masterminded by Kermit Roosevelt, and their chance soon came. -- p. 151

Sampson continues:

Whether and when Mossadeq would have fallen without this covert operation is hard to establish, but what is undisputed is that the Western powers did intervene, and hastened his end. It was a well-organized coup, and encouraged the CIA to further adventures, notably in Guatemala; but the West in the end paid a heavy price for it. For the Shah was thereafter determined to show his independence, and could never again dare to be seen as the pawn of the West. -- pp. 151-2.

Thus, even before the overthrow of the Shah in 1979, the big picture was available to be known. However, there was limited interest in the story in the US at that time. Most public attention was focused on the Cold War and people in the US tended to see any opposition to US policy as the operation of proxies of the Soviet Union.