CBS news anchor Katie Couric is leaving the “CBS Evening News.” (Danny Moloshok/REUTERS)

The second-most drawn-out transition of our time — behind only the Queen Elizabeth –to- Prince Charles throne-of-England hand-off — inched forward Tuesday when Katie Couric said Tuesday she was leaving the “CBS Evening News.”

“After weeks of widespread speculation about her future, Katie Couric is finally ready to go on the record,” reported breathlessly as a wind-up to its “scoop”:

“I have decided to step down from the ‘CBS Evening News,’ ” Couric told exclusively.

“I’m really proud of the talented team on the ‘CBS Evening News’ and the award-winning work we’ve been able to do in the past five years in addition to the reporting I’ve done for ‘60 Minutes’ and ‘CBS Sunday Morning,’ ” added Couric — who, coincidentally, should be now be in London to cover the marriage of Prince Charles’s uber-popular eldest son, Prince William, to commoner Kate Middleton!

“In making the decision to move on, I know the Evening News will be in great hands.”

CBS News thinks so too:

“There’s a lot to be proud of during Katie Couric’s time at Evening News. CBS News, like Katie herself, is looking forward to the next chapter,” the network news division said Tuesday in a statement.

This works out nicely for CBS News, which planned to announce, maybe as soon as next week, that longtime “60 Minutes” correspondent Scott Pelley is the Evening News anchor going forward. Fager’s choice to anchor the evening news going forward. Couric’s contract on the gig expires in just weeks, and it had been widely speculated that new CBS News Chairman Jeff Fager had other plans for the newscast.

CBS wants to announce Pelley in time to be able to talk him up, and maybe trot him out, when the network unveils its plans for next season to advertisers at its annual Carnegie Hall “upfront” bash on May 18.

Katie’s Tuesday announcement was a bit of a dud, since everyone is already about a lap ahead of her, speculating what will be her next gig.

This week’s betting has ABC in the lead for that honor — if only because ABC stands to lose the most when Oprah hangs up her tiara and resigns as Queen of Daytime Talk TV, in order to focus her full attention her ratings-lean OWN cable-network co-venture with Silver Spring-based Discovery Communications.

“Oprah” airs on many ABC stations around the country, including WJLA in Washington . And Oprah gets a lot of credit for bolstering early-evening newscast numbers on those local TV stations, which, in turn, helps ABC’s prime-time ratings.

Syndicators have been chatting up Katie as part of their hunt for The Next Oprah. While “Katie” and “evening newscast” did not turn out to be a great fit, she’s practically legendary as the former Queen of Morning Infotainment TV, having reigned supreme from 1991 to 2006 on NBC’s “Today” show. If anybody can replace Oprah, it’s Katie, syndicators bet, reasonably.

But Katie’s looking for a gig that will also keep one of her feet in the news business, according to nearly all accounts. Can you imagine being the ABC News exec who has to wrangle Barbara Walters, Diane Sawyer, George Stephanopoulos AND Katie Couric? The mind reels.

So what did Katie reveal to People about her next gig?

“I am looking at a format that will allow me to engage in more multi-dimensional storytelling,” she told People coyly, adding that other details, including when and where the show will air, are “still being discussed.”

Later Tuesday, Katie went on Tavis Smiley’s PBS talk show and hinted harder:

“ I think that I’m excited about the future and about doing something that’s just a little more in my wheelhouse,” she told Tavis.

“While it was such a privilege to sit in that chair that once was occupied by Walter Cronkite, it’s a pretty confining venue. And I think I’m looking forward to doing what I think I do best, which is interacting with people, interviewing people, having sort of more extended conversations.”

“Sounds like a daytime talk show,” Tavis said.

“Well, you know, that’s something I’ve been looking at. I haven’t sort of decided completely that that’s what I’d like to pursue, but certainly it does seem like that might be a really good venue for my particular skill set,” Katie answered.

So, what went wrong with Katie and CBS’s evening newscast? There have been loads of stories about Katie not fitting in to the CBS News culture since she joined in ’06. And since CBS Corp. chairman Leslie Moonves named Fager to the newly created position of CBS News chairman in February, Katie’s role as anchor of the nightly newscast was starting to look a little Camille-ish around the edges.

And, of course, you can’t overlook her $15 million-a-year salary. That’s investing at a level that demands progress. Katie Couric anchoring the “CBS Evening News” did not deliver much progress, ratings-wise. As one navel-gazer put it, when you spend that kind of coin, you expect you’ve bought a game changer.

In his final TV season as anchor of CBS’s evening newscast, Dan Rather averaged about 7.5 million viewers, well behind NBC’s 10.6 million and ABC’s 9.7 million. Among the 25-to-54-year-old viewers who are the bread and butter of news-programming ad sales, Rather’s newscast also finished third.

Since then, all of the broadcast-TV evening newscasts have experienced audience declines, as viewers opt for one of the many other news options now at their fingertips.

This season to date, Katie Couric’s evening newscast is averaging around 6 million viewers, in third place, behind ABC’s 8.1 million and NBC’s 9.2 million. She’s also finishing third in the 25-to-54-year-old age bracket, though she’s actually tightened the gap between CBS and ABC a tick — though that may be more about the ABC newscast’s drop than about Katie making gains.

For nostalgia buffs, Couric’s gig on the “CBS Evening News” was a record setter — she was the first woman to solo anchor one of the Big Three TV networks’ evening newscasts. (Barbara Walters co-anchored ABC’s evening news in the 70’s with Harry Reasoner, and Sawyer is now the anchor of ABC’s evening newscast.)

Katie’s tenure included some humdinger interviews — like that one she did with then vice presidential candidate Sarah Palin and asked her which newspapers she read, which got everyone talking.

And who can forget when Katie landed the first interview with red-hot-media-commodity Chesley “Sully” Sullenberger, who had guided US Airways Flight 1549 to a safe landing in the Hudson River after its engines conked out, and all his passengers survived. Katie’s interview with Sullenberger and his crew aired on CBS’s “60 Minutes,” and it was quite the coup for her, since Sullenberger had been set to give his first sit-down to Matt Lauer of NBC’s “Today” show, only it got postponed owing to the official investigation of the watery landing. When the dust settled, Katie had swooped in and nabbed the first interview.

Photos: TV personality Katie Couric

Katie will have more to say tonight about her exit from “CBS Evening News” on Tavis Smiley’s PBS talk show.

Take a look at the preview: