The Duke of Sussex arrived back home, for the first time since he and wife Meghan Markle left for California, on a British Airways flight to Heathrow at around 1.15pm on Sunday, The Sun reported.
He was reportedly met by security off the plane before being driven away in a black Range Rover.
Meghan was advised not to travel from Los Angeles because she is heavily pregnant, according to reports.
It is understood his status excludes him from England’s Covid quarantine rules but that he will isolate for around five days before taking a test privately.
Under coronavirus guidelines, only 30 guests will be allowed to attend, meaning the Queen will have to hand-pick those who will be present at the service.
Around 800 people were set to be invited under planning that took place before the pandemic struck.
Prime Minister Boris Johnson and leader of the opposition Sir Keir Starmer would ordinarily attend such a royal event but will not attend, ensuring their spaces go to members of the Royal Family.
Mr Johnson has already met with ministers, royal representatives and police to discuss plans for the official period of mourning, according to The Sun.
A palace spokesman said the royals would be following social distancing rules throughout, meaning staying two metres from people outside their household or support bubble.
The former Prime Minister John Major said yesterday he hoped the funeral would give the Royal Family an “ideal opportunity” to heal the rifts that have played out publicly in recent months.
“The friction that we are told has arisen is a friction better ended as speedily as possible and their shared emotion and shared grief at the present time because of the death of their grandfather I think is an ideal opportunity,” he told the BBC’s The Andrew Marr Show.
“I hope very much that it is possible to mend any rifts that may exist.”