Prince Harry spent the Queen's birthday lunching in luxury

Prince Harry attended a luxury, alfresco lunch at an exclusive Hollywood club on the day of his grandmother's 95th birthday, the same week of his brief appearance in the United Kingdom.

The Duke of Sussex, who returned to the UK for Prince Philip's funeral, landed back in California a day prior to Queen Elizabeth's 95th birthday.

Harry is said to have lunched with billionaire philanthropist, Wallis Annenberg, 81, at the San Vicente Bungalows on April 21.

RELATED: The three royals who 'didn't greet' Prince Harry at Prince Philip's funeral

The pair were reportedly seen at the art deco private dining facility, known to be a West Hollywood hotspot amongst the elite for it's selling point: "privacy is the new luxury."

Heiress Annenberg is the president of the multibillion-dollar philanthropic organisation The Annenberg Foundation, a charity that has operated in 1989, widely targeting issues of environmental sustainability and climate change, as well as supporting the arts.

A source told Page Six: "they sat outside, far from other people, and Harry came in wearing a mask."

RELATED: Prince Harry's 'special bond' with his grandfather and how he kept in touch from the US

The heiress reportedly "heads her family's multibillion-dollar Annenberg Foundation," and "is also on the boards of USC, the LA County Museum of Art, and LA's Museum of Contemporary Art."

Prince Harry waived his 10-day quarantine in California, a coronavirus guideline which is not compulsory in the United States, and was spotted at the upmarket venue less than 24 hours after his plane landed.

It is unknown whether the Duke of Sussex has received a coronavirus vaccination, which would excuse him from self-isolation.

The Queen celebrated her birthday in a somber fashion, mourning the loss of her husband of 73 years Prince Philip.

Her Majesty was in the midst of her eight days of mourning, following the Duke of Edinburgh's funeral.

The royal family tweeted a statement marking the Queen's birthday, paying tribute to the late duke

"I have on the occasion of my 95th birthday today received many messages of good wishes, which I very much appreciate," read Her Majesty's statement.

"While as a family we are in a period of great sadness, it has been a comfort to us all to see and to hear the tributes paid to my husband, from those within the United Kingdom, the Commonwealth and around the world."

Hello reported Prince Harry and Meghan Markle did send a special gift to the monarch, sharing their birthday wishes alongside their son Archie.

Wallis Annenberg, with whom Harry met, bears connections to the royal family.

As the daughter of Walter Annenberg, an American publishing magnante, the businessman served as the US ambassador to the UK from 1969 - 1974, meeting with Queen Elizabeth and Prince Philip.

The high-profile couples reportedly maintained a close relationship over the years, with the Queen and Prince Philip even visiting Annenberg's home in 1983.