Get it from the horse's mouth!
Get it live! For the live bit you need to find and get into a time-machine, transport yourself back to 27 September 1963 or more likely 1 October and find yourself a spot in the Permanent Subcommittee on Investigations of the U.S. Senate Committee on Government Operations.
If you've already clicked on the from the horse's mouth link, and played the YouTube video to 00:30s, you will have heard Joseph Michael "Joe Cargo" Valachi (September 22, 1904 – April 3, 1971), also known as Joe Valachi - The First Rat proffering the word "godfather" to John Little McClellan (February 25, 1896 – November 28, 1977) during the subcommittee hearings on organised crime held between 25 September 1963 and 16 October 1963.
Joe Valachi: "He, he pricks your finger"
John McClellan: "Who, who"?
Joe Valachi: "The GODFATHER"
Joseph Valachi took few secrets to his grave.
The infamous mob rat unloaded years before his death in 1971, when a mysterious Niagara Falls mistress had his body shipped from a Texas federal prison for burial in Gate of Heaven Cemetery near the Lewiston-Queenston Bridge.
Valachi, a soldier for legendary New York mob boss Vito Genovese, is considered the most influential informant in organized crime history. Valachi was the first to violate omerta, the mob's sacred code of silence, when he testified before a Senate subcommittee in October 1963. He later scrawled some 300,000 words in a scandalous, exhaustive memoir.
His mission: to destroy the underworld brotherhood that betrayed him and put a $100,000 bounty on his head.
Valachi provided what then-Attorney General Robert Kennedy called the "biggest single intelligence breakthrough yet in combating organized crime and racketeering in the United States." Valachi's writings inspired "The Valachi Papers," a seminal 1968 book that helped transform the mob genre into what it is today, from "The Godfather" and "Goodfellas" to "The Sopranos."
His gravelly voice croaked out the words "Cosa Nostra" (roughly, "this thing of ours") in public for the first time. He explained the blood ritual that comes with being a made man and laid out the mob commandments. He was the first to identify the heads of each crime family and the organizational flow chart beneath each one. He dispassionately detailed how contract killings worked and how Genovese gave him the kiss of death.
"There were no more secrets after Valachi," said famous mob author Nicholas Pileggi, whose books included "Casino." "He explained what it was all about. He named names. That's the beginning of the end of organized crime as we knew it.
"Until then, it was a world filled with secrets. After Valachi, the Boy Scouts had more secrets than the mob."
The Permanent Subcommittee on Investigations of the U.S. Senate Committee on Government Operations was chaired by Senator John McClennan who took over from Senator Joe McCarthy in 1955 after he
led a Democratic walk-out of the Republican-controlled subcommittee because of objections to Senator Joseph McCarthy’s witch-hunting conduct. In 1955, McClellan assumed chairmanship and hired Robert F. Kennedy as chief counsel. As chair of that subcommittee and two other investigative committees—the Senate Committee on Improper Activities in the Labor or Management Field and the Special Committee to Investigate Political Activities, Lobbying and Campaign Contributions—he conducted more congressional investigations than any other member.
Under McClellan’s leadership, some of the most well-known and significant investigations in the nation’s history were conducted—probes into widespread corruption and criminal activities in the labor-management field, organized crime, the TFX aircraft contract, profiteering in defense contracts for missile procurement, and the riots that erupted in cities and college campuses in the late 1960s. Inquiries concerning the activities of teamsters Dave Beck and Jimmy Hoffa, the so-called “Valachi hearings,”
My doubt regarding exact dates is caused by my interpretation of an article in the Congressional Quarterly Almanac
Sept. 27 – Valachi, who said he was initiated into the “Cosa Nostra” in 1930, said it consisted of “families,” under the leadership of bosses, each flanked by a lieutenant, who was in charge of an individual gang, or “regime.” Each “regime” consisted of a number of henchmen, who were known as “soldiers.” Valachi said the organization's operations involved extortion, loan sharking, murder, assault and similar criminal endeavors. Valachi said New York gangster Vito Genovese, currently serving the, third year of a 15-year prison sentence for narcotics handling, was the “boss of all bosses” within “Cosa Nostra” and continued to rule the underworld from prison.
Oct. 1 – Valachi continued his testimony, giving the Subcommittee details of his initiation into “Cosa Nostra” and the history of inter-gang warfare for control of the organization
Valachi testified that upon his initiation, which closely resembled that of a young college boy joining a secret Greek fraternal organization, he was contracted to drive the get-away car during the slaying of one-time underworld chieftain Joseph Catania in February 1931. Catania's death and the earlier slaying of Peter (The Clutching Hand) Morello, Valachi related, cleared the way for new “family” leadership within “Cosa Nostra.” Morello's and Catania's successors were Charles (Lucky) Luciano, Philip and Vincent Mangano, Gaetano Gagliano and Joseph Profaci, Valachi said. Ultimately, control of New York's “families” passed to Genovese, Carlo Gambino, Joseph Magliocco, Joseph Bonanno and Thomas Luchese, Valachi alleged.
Turnover in “Cosa Nostra” leadership, Valachi said, was usually accomplished by the “disappearance” of the incumbent leader.
I assume that the YouTube video clip shows his testimony from 1 October 1963.
The following information is from Wikipedia (link in the quote below)
Following Valachi's testimony, the Italian-American Mafia was no longer the organization invisible to the public that it had been for almost a century.
After the Justice Department first encouraged and then blocked publication of Valachi's memoirs, a biography, heavily influenced by the memoirs as well as interviews with Valachi, was written by journalist Peter Maas and published in 1968 as The Valachi Papers
The Valachi Papers is a biography written by Peter Maas, telling the true story of former mafia member Joe Valachi, a low-ranking member of the New York-based Genovese crime family, who was the first ever government witness coming from the American Mafia itself. His account of his criminal past revealed many previously unknown details of the Mafia.
In the Valachi Papers (Google book link with part of the following quote)
mob boss Salvatore Maranzano told him, “’Well Joe, that’s your gombah (Joseph Bonanno).’ - meaning he was kind of my godfather and was responsible for me.”
So finally, to answer the questions
Whom was the epithet first used for in the early ‘60s?
It was used in reference to Joseph Bonanno (January 18, 1905 – May 11, 2002)
Was it originally used in AmE or in BrE?
It was used in AmE
Interestingly, in Italian-American English
goombah – countryman/fellow comrade/godfather (compare) [goom-BAA]
Goombah according to Wikipedia
Goombah and similar forms probably derived as an alteration or Anglicized spelling of the common Southern Italian familiar term of address, cumpà, the apocoped oxytone form of the word cumpari found in Southern Italian dialects and compare found in Standard Italian, which denotes the godfather in a baptism.
is therefore commonly used as a term of endearment roughly equivalent to "friend," "brother," or "comrade" among close friends or associates (generally males) in certain parts of Southern Italy, including Campania and Sicily, where it becomes cumpà or cumpari in the regional Southern languages. It has, however, also gained a less innocuous meaning in certain criminal contexts, signifying an "accomplice," "cohort," "fellow criminal," or "partner-in-crime," though it is still mostly used among non-criminal Southern Italian males as a harmless address of affection.
"Compare" and the Southern Italian "cumpà" and "cumpari" ultimately derive from the medieval Latin compater, meaning "cousin" and, later, "godfather."
With the arrival of Southern Italian immigrants in America, this appellation used among Southern Italian males, cumpà, became the Anglicized "goombah" or "gumba" to American ears. As the term cumpà was commonly heard as an term of address among Italian immigrants and Italian-Americans, the Anglicized version of cumpà, or "goombah," came to be used among non-Italians as a derogatory or patronizing way to refer to Italian-Americans.
Today, especially in Italian-American slang, "goombah" is a slang noun for a companion or associate, especially a friend who acts as a patron, accomplice, protector, or adviser. When used by non-Italians to refer to Italians or Italian-Americans, however, "goombah" is often derogatory in nature or deployed as an ethnic slur, implying a stereotypical Italian-American male, thug, or Mafioso.
Mental Floss in an article entitled 10 Gangster Pieces of Mob Lingo has the following to say about godfather
While godfather isn’t part of the GoodFellas lexicon, a roundup of mob slang wouldn’t be complete without it.
The original meaning of the word, a male godparent, is from the 13th century, while around 1830 it also came to mean “an influential man.” As for godfather referring to a mafia leader, in a 1997 interview, Godfather author Mario Puzo claims to have invented the term: “It was never used for a criminal figure ... The term didn’t exist before I used it.”
The OED would beg to differ. While the Godfather novel was published in 1969, the OED includes a citation from a 1963 transcript of a government hearing: “Are you the godfather of any other member ‘made’ since then?”
As for why terms like godfather and goodfella began appearing in English print in the early 1960s, that could point to the Apalachin Raid, which occurred on November 14, 1957. A group of mob bosses were holding what they thought was a clandestine meeting in New York State, only to be ambushed by a suspicious state trooper and other law enforcement. After the raid, the existence of the mafia became common knowledge.