honestly I think that the Royal Knockout was mild compared with the silly behaviour that Sarah indulged In...I between the two of them.
I remember the two couples on the annual skiing trip, Diana and Sarah started play tussling and Charles was extremely upset with the action. Then there was the disasterous "It's A Royal Knockout" tv show. Apparently, Diana wanted to appear with the Yorks, etc. and Charles put his foot down and stopped her. That was the wisest decision Charles made. I have British neighbors and we talked about that show one time years ago and they said Sarah made an absolute fool of herself and of course, Andrew, Anne and Edward weren't in the best spotlight either.
It's sad that Diana and Sarah were on bad terms at Diana's death, but I've written, Sarah goes too far and alienates herself.
OK it was stupid but it was for charity.. but a lot of Sarah's silliness was as you say increasingly "vulgar" and self indulgent.. and increasingly less harmless.
she did things like books that she said were for charity, but then used the money for herself.. She had affairs, and got caught at them.. and again, one of the attractions of her 2 lovers were that they were rich or said that they could make her rich..
She just is terribly silly and very early on, like the hen night, she was doing stuff that was so stupid, like dressing as a policewoman and possibly shutting the BP gates for a lark.. that you'd think someone would have really put their foot down with her and told her she had to be more careful, but I have heard that couriters said " we DO tell her what to do but she wont listen"...and I think that is true,.
Its nothing to do with who her father was, it is to do with the fact that she - in spite of having "good connextions", DIDNT seem to have a clue how to behave... and aciting like she had never had any "upbringing"...
If she had been "the daughter of a stable boy", well perhaps there might have been some excuse for her not knowing how to behave, but she wasn't.. She had gone to a good school, she was born to a "good family" as regards social connections, she had mixed with the RF on and off and was part of the upper classes, yet she really was utterly lacking in any self restraint or good manners.
she just did what she liked, regardless of consequences and even now, she is pretty silly and clearly can't manage money..ANd she DID seemed to "lead" Diana into silliness that might have damaged Di's pristine reputation at the time.. Di I think was smart enough to work out within a short time that the behaviour was vulgar and stupid ad that it was getting her bad headlines and I think that she was willing to cut off being seen with S in public..
After a short while she stopped the silly antics, but remained close to Sarah for a while. However they had the row over the shoes remark, and Di seems to have really rather unkindly refused to ever forgive her for it.
but as you say Sarah DOES tend to just go too far and doesn't know when to stop and perhaps if Di was unhappy and fed up, and felt thtat she had lost an ally because of the veruccas remark, she found it hard to forgive Sarah...