April 21 marks the 90th birthday of Queen Elizabeth, who was born in 1926 and ascended the throne in 1953. Six decades after her coronation, the Liz Biz is as strong as ever.

To royalists, she is the symbol of British perseverance and tradition, respected for everything she does and embodies. To some others, she is an ideal brand.

On Feb. 11, 1953, Variety outlined plans for her June 2 coronation. Aside from extensive coverage on television (which was pretty new in those days), the event would be the subject of three film documentaries, including one in 3-D. The BBC announced it had assigned “every available camera and technician to the job.” The viewing audience in Britain alone was expected to reach 27 million — more than half of the total population.

Multiple black-and-white cameras would cover the procession, many of them for newsreel companies around the world; inside Westminster Abbey, news coverage would be pooled. In the U.S., CBS and NBC had an intense rivalry over which could offer the best coverage; however, in the days before satellite transmission, U.S. stations could only offer a kinescope version the following night.

Britain’s enthusiasm was at a fever-pitch, which spread to the States. Variety reported, “Since the advent of trans-Atlantic air travel, Londoners have become accustomed to an influx of American tourists, but there has never previously been such a concentration from across the pond.”

Not everybody was enthused about the Yankee presence. During the opening-night performance of the new musical “Guys and Dolls,” the audience was generally receptive, but there were some boos from the balcony. Variety speculated that it was due to the large number of Americans on stage: “It was an example of misplaced British pride and patriotism.”

Variety covered the royal events from a showbiz angle. It ran the headline “Queen Liz Whoop-De-Doo” while the story referred to the thriving “Liz Biz.” A columnist in London’s Sunday Express lamented it as the most tasteless headline of the month.

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But the Liz Biz continued for many decades. She was the subject of songs by such groups as the Beatles, Sex Pistols and Pet Shop Boys, and she was spoofed on the Brit series “Spitting Image,” and in the “Naked Gun” and “Austin Powers” movies.

Her most famous depiction was in the 2006 film “The Queen,” written by Peter Morgan and starring Helen Mirren (who won an Oscar); the duo repeated those duties in the 2013 play “The Audience.” (Stephen Frears directed the film, Stephen Daldry helmed the play.) In November, Netflix will bow the 10-episode “The Crown,” reuniting Daldry and Morgan, with Claire Foy playing Elizabeth.

There are too many depictions of QEII to mention all of them, but the most notable was when she played herself, co-starring with Daniel Craig in a segment for the Danny Boyle-masterminded 2012 Summer Olympics opening.

Is it disrespectful to say that she is a triumph of marketing? Of course. However, consider the fact that there are 12 sovereign monarchies in Europe, but most Americans (and many other citizens around the world) can name only one. This branch of the royal family has had a longer run than “EastEnders” and “Dynasty” combined, with as much drama as “Empire” and “Game of Thrones.”

She holds the record as Britain’s longest reigning monarch (last September, she passed Victoria’s record) and is the oldest ruler. But in an article this week in the Guardian, royal expert Stephen Bates reminds that no one is allowed to say the A word in her presence: abdication. He says the royals still haven’t recovered from the abdication in 1936 of “uncle David,” aka Edward VIII, which Bates describes as “the worst crisis in the monarchy’s modern history.” When she does exit the throne, King Charles III will become the oldest person ever crowned; he’s already 70.

Bates, who covered the royal family for years, has a new book titled “Royalty Inc: Britain’s Best-Known Brand.” Long live the Liz Biz.