Amid the rumoured rift between Queen Elizabeth and Kate Middleton, recent news revealed that the longest-reigning monarch has invited the Duchess of Cambridge to her landmark occasion on Sept. 9.

In its report, the Mirror stated that the 33-year-old wife of Prince William will finally be out once again to attend a special gathering.

The article added that the parents of two-year-old Prince George and three-month-old Princess Charlotte have received an invitation from the royal matriarch for a "family dinner."

The celebration, which Kate Middleton will personally witness, is expected to make headlines in various news outlets since it will mark Queen Elizabeth's acceptance of the crown of longevity from her great-great grandmother Queen Victoria who remained in power for 63 years and 213 days.

It can be recalled that the mother of two has been away from the public's eyes since she gave birth to Princess Charlotte in May. In fact, she was not able to make it to the wedding of her friends Bear Maclean and Daisy Dickson.

Meanwhile, Mail Online reported that the landmark occasion will happen in the Queen's Scottish home at Balmoral.

"The Duke and Duchess of Cambridge will be with the Queen at Balmoral on Sept. 9," an unnamed source told the site. "They will attend a family dinner that Her Majesty will give that evening."

Along with the presence of Kate Middleton and Prince William in the occasion, news about the release of the Queen's biography was also noted.

In the said manuscript by former Foreign Secretary Douglas Hurd, the Duke of Cambridge did a "deep tribute" to Queen Elizabeth, as he wrote the foreword which talked about Her Majesty's "example and continuity" throughout her reign.

In other news, the Mail Online also shared the "flattering new portrait" of Kate Middleton by Brazilian artist Fabiano Millano where she was shown with her glowing and sweet beam.