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Notorious gossip queen Joan Rivers is at it again and, as usual, no one is off limits when it comes to her jokes.

The 79-year-old comedian shocked British viewers Friday when she took a dig at the late Princess Diana on a British-themed episode of her late-night E! talk show, "Fashion Police."

'If you ever want to go to Paris, fly don't take the tunnel," Rivers said on the show.

The comment was referencing Princess Diana's death in 1997 when she crashed in a tunnel during a high-speed car chase.

The usually outspoken comedian was critiquing Kate Middleton, wife of Princess Diana's son William, when she made the joke.

Rivers' comment shocked fellow hosts, and Brits Kelly Osbourne and Cat Deeley.

Rob Shuter, host of "Naughty but Nice" on AXS Live and friend of Rivers, wasn't surprised by the comedian's Princess Di dig.

"Joan is not one of those people that censors herself," Shuter told ABCNews.com. "If she thinks it's funny, she's going to say it."

The comedian, who has made jokes about everyone from Michael Jackson to Whitney Houston, believes nothing is off limits, Shuter said. But the Diana joke launched backlash among British viewers.

"There are plenty of other subjects to make fun about in a show about fashion," British viewer Andrew Henry told the Daily Star magazine. "But that was one step too far. Cruel, vicious and disgusting."

Shuter said, "In Britain it's very shocking. It's a very different sense of humor over there. I think we're used to Joan in America."

Rivers has had a long relationship with Prince Charles, Shuter said.

"She took Kathy Griffin to Buckingham Palace," Shuter said. "That tells you that Joan Rivers knows them very well."

The Princess Diana comment was not out of character for Rivers, who Shuter insists has a heart of gold. "When you take these jokes out of context, they're really jarring," Shuter said.

"You have to remember the source and it's Joan."