Hundreds attended the charity event which took place in Vauxhall, South London.
The old report comes after news that Kate's sister Pippa Middleton was once dragged into the Duchess's feud with Princess Beatrice and Princess Eugenie.
According to another unearthed reports, the princesses spurned Pippa in public in 2008.
It all went down when Kate was still dating Wills, and the mother-of-three and her sister attended a fashion show for Issa, which was also attended by Bea and her sister, Princess Eugenie.
Looking back at the event, Ostler wrote in an article for Daily Mail in 2016 and revealed: “Organisers asked an already seated Beatrice and Eugenie to shuffle up in the front row to make room for Pippa Middleton."
“It is said they refused," the insider added.
“Depending on who you talk to, this was a case of the Princesses being regal and unfriendly or Pippa being unnecessarily pushy because she didn’t want to lose face by suffering the social death that is being made to sit in the second row.”
A society girl who was present revealed to the publication: “Pathetic, maybe, but however you look at it, people remember these things.
“They deplete mutual goodwill, if there is any to begin with.”
Pippa and Bea appear to have moved on from the incident.
After Beatrice threw an engagement party last year to celebrate her engagement to Edoardo Mapelli Mozzi, Pippa was in attendance, along with her husband James.
Kate, however, was a no show at the celebration at London's Chiltern Firehouse in December 2019.