Members of Parliament forgo normal House business in a special session to pay tribute to the late Duke of Edinburgh, Prince Philip.
The Duke of Cambridge will not be reunited with Prince Harry until the day of their grandfather's funeral, when the Duchess of Cambridge is expected to act as peacemaker between the royal brothers.
The siblings are understood to have spoken on the telephone since Harry landed in the UK on Sunday, and hope to finally see each other in the flesh on Saturday morning, ahead of the 3pm ceremony at Windsor Castle.
It will be their first face-to-face meeting in more than a year and comes after Harry and Meghan gave an interview to US chat show host Oprah Winfrey suggesting an unnamed royal had queried Archie's skin tone as well as describing William as "trapped" in the monarchy.
Sources close to both couples insist that they will be putting their differences aside for the sake of the Queen as the family gathers at St George's Chapel to remember the Duke of Edinburgh, who died on Friday, aged 99.
As one royal source put it: "They know it is not about them on Saturday - it is about honouring their grandfather's memory and supporting their grandmother.
The Duchess of Cambridge, who Harry described as the "big sister I never had" when she became engaged to William in 2010, will help to broker peace between her husband and brother-in-law.
Kate, 39, was said to be "hopeful of a reconciliation" with Harry and Meghan before the Oprah interview, telling friends she did not think it was too late to "pull them back in".
During last month's prime time two-hour tell-all, Meghan accused Kate of making her cry during a bridesmaid's dress fitting before her wedding to Harry in May 2018 and questioned why she had not acted to correct reports it was the other way round. She said Kate "owned it and apologised" with a handwritten note and flowers.
Claims later emerged suggesting Meghan had slammed the door in Kate's face when she made the peace offering on the doorstep of Nottingham Cottage, the Sussexes' former home at Kensington Palace.
With pregnant Meghan unable to attend the funeral on doctor's advice, it is hoped that Kate may be able to foster a rapprochement, believing it to be "incredibly sad" that William and Harry are not on better terms.
Kate Middleton could help heal the rift between the brothers ahead of their appearance at Prince Philip's funeral. Photo / Getty Images
According to one source: "Being so close to her own siblings, Pippa and James, and having witnessed first-hand the special bond between William and Harry, she has found the whole situation difficult and upsetting."
More introverted than her public persona might suggest, the level-headed duchess has been credited with "taming" William's sometimes fiery emotions since they married a decade ago.
Unlike her husband, who is a "bit of a news junkie", the mother-of-three tends to shy away from press coverage and has gained a reputation for her unflappability in the face of a royal crisis.
William "hit the roof" when paparazzi photographs emerged of his wife sunbathing topless during a private holiday in the south of France in 2012 but Kate largely shrugged it off. When the couple won €100,000 ($179,327) in damages from Closer, the French magazine that published them, they donated the money to charity.
The source added: "She is certainly someone who shies away from conflict and will be hoping to soothe the tensions."
Meghan's friends have suggested she is willing to put the past behind her and turn over a new leaf in her strained relationship with the royals.
They said the duchess believes Prince Philip would want to see the broken bridges mended. The Sussexes' second child, a girl, is thought to be due as early as June - another opportunity, perhaps, to bring the family together, albeit via transatlantic video call.
Kate is said to be hoping for a reconciliation with Meghan and Harry. Photo / Getty Images
After flying from Los Angeles on a scheduled BA flight and landing at London's Heathrow on Sunday lunchtime, Harry is currently quarantining at Frogmore Cottage, his former Windsor home, where he is required to remain until Friday at the earliest.
Although he will be allowed to attend his grandfather's funeral regardless "on compassionate grounds", he can only leave self-isolation after five days rather than 10 for another reason if he provides a negative coronavirus test under the Government's "Test to Release" scheme.
Because he has to take a PCR test, rather than a more rapid, lateral flow test, which produces a result in minutes, it is unlikely he will be confirmed as negative for Covid until Saturday morning.
The Duke and Duchess of Cambridge are currently spending the Easter holidays at Amner Hall, their Norfolk home, with their three children Prince George, 7, Princess Charlotte, 5, and Prince Louis, who turns 3 later this month, and are not due back in London until the end of the week.
With the guest-list limited to 30 under the latest government coronavirus guidelines on indoor worship, no great-grandchildren are believed to be attending the funeral.
It is thought the Cambridge children will return to Kensington Palace with their parents to prepare for the start of the summer term on Tuesday. This would potentially give them the opportunity to see "Uncle Harry" outdoors before he returns to the US.
Yesterday a spokesperson for Harry declined to discuss his movements after the funeral but said he would be "following Covid-19 guidance" throughout his stay in Britain.
