I think this is now the busiest time in Mrs. Middleton's business...
Interesting scenario, Jo. While we're speculating, can I propose another?
A journalist introduces himself as a business reporter from the Telegraph and asks Ms. Middleton for an interview on her business. She says she's interested (it is after all the Christmas season) but she says she's concerned it will mostly be about her daughter's relationship with Prince William and she doesn't want to go into that. So she offers to the reporter what she wants to be the focus of the interview (maybe something about what her company can offer during the Christmas season that others can't, or tips for planning a holiday party, or the challenges that Internet businesses face meeting demand during the holiday season) or she asks the reporter what the planned focus of the interview is. The conversation goes on as the two work out what will be covered and Ms. Middleton still a bit concerned that Kate will still be the focus of the interview and restates that discussing Kate's relationship with William is offbounds. She doesn't mind if they mention that Kate is dating William, after all, that is why they're coming to her, but she doesn't want the interview and the article to focus on Kate. The reporter either assures her that she won't have to talk about Kate or says 'Listen, my editor will kill the story if I don't ask you some questions about Kate'. In that case, Ms. Middleton either agrees to consider the interview or she decides to turn it down. If the reporter is actually not the business reporter then Ms. Middleton figures out that the person has no clue about giving a business interview and ends the conversation right there.
Well obviously this scenario didn't happen, but it would have been the most logical one if a person claiming to be a business reporter asked Carole Middleton for an interview in a well-respected paper.
There is another scenario that I think may be more likely. A reporter from the Telegraph had previously approached her about doing a story about families of people that find themselves in the limelight and the effect the publicity has on other members of the family. Previously, Ms. Middleton has turned the offer down. Kate is still serious with William and the royals are a little paranoid about families of prospective girlfriends talking and she doesn't want to sabotage Kate's relationship with Wills. However, in the meantime her name has been dragged through the papers and its starting to affect her other children, and Kate is starting to have problems with William. At first it doesn't seem serious, but as time passes by, the maternal instinct tells her this relationship is on the rocks and about to end.
At this point, she and her family have been under press scrutiny for years and she personally has been the target of some pretty nasty press. Its affecting her other children and she may be angry as a mother with the way William has been acting towards her daughter and the perceived lack of support from the Royal Family. The free publicity helped in the beginning but while she got more hits on her website they didn't turn into appreciably increased sales which is what pays the bills. The only advantage to the whole press scrutiny, free publicity for the website is not turning into sales which with the downturn in the relationship is turning the whole scenario as a negative for the family.
So she decides that this is the time to do the interview, first because the reporter has been so sympathetic and understanding over time and secondly so she can say all the things that she's wanted to get off her chest but held off on, because it would hurt Kate's chances with William. She doesn't mention her thoughts about a breakup because she knows that will hit front page and will totally drive out what she wants to say about the effect all the press scrutiny has had on her family. She keeps the interview focused on her family and her business and her other children outside of Kate.
She gets her point across in the interview before a breakup announcement and its a pretty sympathetic article.