End of an era: Larry King in last CNN broadcast

But Thursday night Larry King is hanging up his famous braces, turning off that broad-toothed smile, and shutting down the hour-long interview show that was a feature attraction on cable TV news channel CNN for over 25 years.

There are many reasons for his decision to end one of the longest remaining tenures in major television.

The guy, after all, is 77 years old and underwent a horribly messy divorce scandal recently with his seventh wife, who tried to commit suicide before they resolved their differences and decided to stick together.

But there are also powerful professional reasons to dim the lights on "Larry King Live", a nightly show that more than any other helped define CNN as the marquee 24-hour international news channel.

Most importantly, the old geezer's laid-back approach to interviewing has been superseded by a tougher more combative and opinionated style personified by the likes of Fox TV's Bill O'Reilly.

In recent years, King has had to suffer the ignominy of placing third in the ratings in his time slot behind interviewers who were not even a twinkle in their parents' eye when King was already a star.

While other interviewers take pride in confronting their guests and beating them into submission, King has been known in the US for his softball style - lobbing up easy questions for his guests to answer as they please, while he leans forward to listen with an expression of rapt fascination.

After a long career in talk radio, King debuted his show on CNN in 1985.

According to Bob Thompson, a professor of popular culture at Syracuse University, King rarely made history in his interviews, but the sheer mass of over 50,000 interviews will represent a massive trove for future historians studying the period.

"The true legacy of the Larry King Show was the booking department. They had an unmatched ability to get people who were at the centre of the zeitgeist," said Thompson.

"No-one ever said that King was a great journalist, but nevertheless it was interesting to get these people in long-form interviews which are now part of the historical record.

People who study that will find a monumental body of work."Indeed, his most memorable shows blurred the line between human interest and politics.

On his show even Margaret Thatcher sounded normal, Marlon Brando seemed relaxed and Monica Lewinsky gave her first interview about her relationship with former president Bill Clinton.

King often boasted of his lack of preparation for interviews as a way of ensuring he would ask the simple questions the public was interested in. But critics claimed that the lazy technique prevented him from getting to the heart of many issues, and left King open to charges of ignorance.

One of the most famous debacles came in 2007 when he asked comedian Jerry Seinfeld whether his show had been cancelled by the network.

"You think I got cancelled?" Seinfeld replied in amazement. "Are you under the impression that I got cancelled? I thought that was pretty well documented. Is this still CNN?" Seinfeld went on, "It was the No. 1 show on television, Larry. Do you know who I am?"