Prince Philip and Queen Elizabeth II are, currently, self-isolating inside Windsor Castle. The royal couple relocated to the Berkshire county in mid-march to eliminate the risks of contracting the novel coronavirus.

But, as the pandemic crisis continues to wreak havoc across the globe, the Queen and her husband will reportedly remain in isolation. It remains unknown, as well, until when they would stay behind closed doors.

Amid the crisis in the United Kingdom, Prince Philip and Queen Elizabeth II will reportedly mark two important dates this month. While they observe the lockdown measures, the royal couple will have their "celebrations," according to the Daily Express.

As stated, Prince Philip will turn 99 on June 10. This is a huge "milestone" for the royal couple, especially for the Duke of Edinburgh, as he is now much closer reaching his 100th year.

While no huge celebrations are in place, sources reportedly shared that the royal couple will mark the day together with a simple "lunch" inside Windsor Castle. Also, the reports added that they will spend the rest of the day virtually communicating with some members of the British Royal Family.

Through video conferencing with the use of the Zoom platform, Prince Philip and Queen Elizabeth II will reportedly call Prince Charles from Birkhall, in Scotland. Sources also went on to assert that they will call Prince William and Kate Middleton, as well, in Anmer Hall. Although they are miles away from the United Kingdom, Meghan Markle and Prince Harry will also reportedly get a video call from Windsor Castle. 

Aside from the video calls, the publication also said that a "small number" of "public birthday" greetings and wishes will be posted on social media platforms. Nevertheless, Buckingham Palace reportedly "hopes" to celebrate the day "publicly" in some small and safe way.

Despite the hopes, though, the whole celebration will still reportedly depend on Prince Philip and how he "feels" to mark his special day. As stated, his "mantra" for that day is "low key."

Meanwhile, Queen Elizabeth II will also reportedly celebrate another milestone as they continue to self-isolate. As explained by the Daily Express, the Queen's coronation took place on June 2, 1953.

So, days prior to the Duke of Edinburgh's birthday, celebrations are also in place to mark the Queen's milestone. It remains undisclosed, however, how they will celebrate the day.

Since her coronation, Queen Elizabeth II has reigned for 67 years as the head of the British Monarchy.