Now that Harry's back in the UK questions remain over when and how he'll reunite with his family

Prince Harry is now in the UK, having flown in from California to attend the funeral of his grandfather Prince Philip.

But it's unclear exactly how and when the Duke of Sussex will reunite with his family.

Harry is having to undergo five days of quarantine due to UK Government regulations in place because of the coronavirus pandemic.

READ MORE: Why Prince Philip's death is a loss for not only the Queen but the world: His remarkable legacy as the People's Prince

A legal loophole will allow Harry to leave quarantine to attend the funeral on Saturday April 17 early, but he will be required to return to self-isolation immediately afterwards.

The full quarantine period in the UK is 10 days.

The provision in the law permits people to leave quarantine on "compassionate" grounds, which includes funerals.

Harry reportedly arrived in London on Sunday afternoon local time on board a commercial British Airways flight before he was whisked away by security in a Range Rover.

He is understood to have taken a COVID-19 test in the US, and received a negative result, allowing him to travel.

Under England's current rules, travellers can leave self-isolation only if their tests are negative.

Harry is understood to be quarantining at Frogmore Cottage in Windsor.

READ MORE: Prince Philip's death 'peaceful' like 'someone took him by the hand' says Sophie, Countess of Wessex

The duke still has access to Frogmore Cottage, which he and Meghan lived in soon before Archie was born.

He will officially reunite with his grandmother the Queen, his father Prince Charles and brother Prince William on Saturday.

It remains to be seen if he will be able to see his family prior to then.

England's coronavirus rules also state that the Queen and her family must wear face masks during Prince Philip's funeral.

They must also socially distance from one another if they are not part of the same household.

Sir John Major, who was appointed special guardian of Prince William and Prince Harry after the death of their mother, hopes the shared grief over Prince Philip will "mend any rifts" within the royal family.

Sir John, who is also former British Prime Minister, said he hoped it would end any "friction" between the brothers.

"The friction that we are told has arisen is a friction better ended as speedily as possible," Sir John told BBC One's Andrew Marr Show.

He added: "They shared emotion. They share grief at the present time because of the death of their grandfather. I think (this) is an ideal opportunity.

"I hope very much that it is possible to mend any rifts that may exist."

Saturday's ceremonial royal funeral will be the first time Prince Harry has seen his brother, father and his grandmother face to face, since his and Meghan's interview with Oprah Winfrey.

Prince Harry's last royal engagement with his family was at the Commonwealth Day service at Westminster Abbey on March 9, 2020.