Many of Camilla's personal friends, family members and even former staff were at the party too along with her ex-husband Andrew Parker-Bowles and her sister Annabel Elliot.
That's what a lot of fans can't help but wonder as the Duke and Duchess of Cambridge's names seemed to be left of the guest list of Camilla's party.
Speaking about snapping Camilla for her 70 birthday, Testino said: "I'm honoured to document Their Royal Highnesses The Prince of Wales and The Duchess of Cornwall on this very important date". On Thursday, she and Charles welcomed charity friends to mark Camilla's contribution to the world of royal duty - something she didn't start until marrying Charles in 2005 at age 57.
The society stylist, although officially retired from the salon, still sees his favourite clients privately and is the only man the Duchess trusts to tend to her locks.
Twelve years after their controversial civil wedding, which followed years of public rancour over their relationship, the portrait makes clear that they are very much a partnership of equals as they move, albeit reluctantly, ever closer to the throne.
Her own image with the public has also improved from a low point after the death of Diana, Princess of Wales, in 1997.
There is still debate about whether the general public would accept her as Queen when Prince Charles becomes King.
The official title for her when that time comes is HRH The Princess Consort.
In the soft-focus photograph, Camilla looks relaxed and happy, with her soft blonde hair do and natural make-up reflecting her low-key approach to style.
Prince Charles and Camilla, Duchess of Cornwall, have unveiled their official portrait ahead of Camilla's 70th birthday on Monday.
The Duchess was recently filmed by ITV News cameras having a fit of giggles watching some traditional throat singing on tour in the far north of Canada.
The future Queen of England is pictured smiling widely next to here husband of 12 years, Prince Charles, 68, in the portrait picture.