Later on Saturday, a birthday party for the Duchess will be staged at the Prince's Highgrove home in Gloucestershire, with a large gathering expected at the private event. Charles went on to marry Diana Spencer in 1981 but within a few years he had returned to Camilla, conducting an extra-marital affair, as Princess Diana also sought comfort from officer James Hewitt.
There is still debate about whether the general public would accept her as Queen when Prince Charles becomes King.
Camilla will be spending tomorrow privately with her family, including her two children, Tom and Laura, and her five grandchildren, and - if he can be persuaded not to work - her husband, the Prince of Wales.
And Charles' display of devotion to his second wife, whom he married in 2005, didn't end there.
Providing an insight into the physical toll a life of royal engagements can take, Camilla said her footwear could often cause discomfort.
In April constitutional expert Lord Norton of Louth, a peer in the House of Lords and professor at the University of Hull, told Sky News the constitutional position is very clear. But if she wishes to be known by another title, that's a matter of royal prerogative, so the monarch could determine that another style will be employed.
Some suggested it was a nod to the public mood about their relationship and the death of Princess Diana.
Obviously there are people who will never like Camilla as they see her as the person who broke up the marriage.
Much favoured by the wider royal family, Testino, 62, was also the first choice for Camilla's birthday shot having photographed her and the prince on several occasions each over the years.
"Doing this latest assignment to celebrate Her Royal Highness's 70th birthday is a true honour".
Camilla celebrated becoming a septuagenarian with two parties over the last week and held a garden party for her staff and her many charities on Thursday at Clarence House in London.