Zara Phillips is waltzing into a right Royal storm after signing up to compete in the next series of Strictly Come Dancing.
Zara, 27 - the Queen's granddaughter and 12th in line to the throne - has agreed to become to first royal to appear in the BBC1 ballroom series this autumn.
A source close to Zara - fiancee of rugby World Cup hero Mike Tindall - said:
"People are pinching themselves at the idea that this is actually happening.
"The Queen may have something to say about Zara appearing on a live TV show every Saturday. Many in Royal circles will find it inappropriate."
But BBC bosses are said to be thrilled at the signing - seen as a shot across the bows in the Saturday night ratings war with The X Factor.
One said: "The idea of getting Zara involved was floating around for a while but no one thought it would come off.
"Last year's line-up was pretty strong, but signing a royal is a trump card in the ratings battle. Who can resist switching on, just in case Wills and Harry drop in to wish their cousin good luck?"
Insiders believe the series will help Zara get over her disappointment at having to pull out of next month's Olympics.
The showjumper has to miss this year's Olympics in Beijing after an injury to her horse Toytown - a repeat of what happened before the Athens Games of 2004. But Zara's involvement in the reality TV show - which more than 10million fans tuned in to last year to see ex-Mis-Teeq singer Alesha Dixon and partner Matthew Cutler win - is likely to cause deep embarrassment to the royals.
Zara's brother Peter found himself in hot water last month after "selling" coverage of his wedding to Hello! magazine.
But the Palace is powerless to intervene because Zara is not titled.
Her mother Princess Anne refused to give her children royal titles in a bid to help them lead normal lives.
It means Zara is free to exploit her status for commercial gain. She was the first royal in line to the throne to appear in an ad, promoting Land Rover, two years ago.
A bbc spokeswoman said last night: "We can neither confirm nor deny the speculation around contestants at this stage."
But a source confirmed Zara has signed an "early stage" contract called a "letter of intent" to appear on the show.