Boris Johnson will not be attending the 20th anniversary memorial of the 9/11 attacks in New York in person this weekend, but will instead mark the occasion from his official country residence, Downing Street said.
Asked whether Johnson was invited to visit New York – the city of his birth – as part of commemorations, the spokesman said: “I believe our ambassador in Washington will attend the memorial event in New York and lay a wreath.”
But how can we take part in commemorations, and how can we watch the event in the UK?
Here is everything you need to know.
What is happening at Ground Zero?
Since 2002, each year on September 11, the names of the dead have been read at the event at the famous memorial pools, an event previously attended by Presidents Bush and Obama.
The service will play out similarly this year, but in a more intimate format.
Commemorations will take place on 11 September at the National September 11 Memorial & Museum in New York City, starting at 1,30pm UK time.
But with areas of America - including New York City - still grappling with the Delta variant of Covid-19, the service will be a scaled back affair with in-person attendance limited exclusively to 9/11 family members.
That limited guest list has angered some, with it excluding first responders, survivors and others from the events.
But organisers insist the policy hasn’t changed from previous years, with only the family members of 9/11 victims receiving “formal” invitations in the past.
“Only family members are invited,” memorial spokesperson Lee Cochran told the New York Post, adding: “The invited family members can bring as many additional family-member guests as they’d like.”
Jim Riches, a retired firefighter whose firefighter son was killed in the attacks, has attended every 9/11 ceremony and said many first-responders were admitted even without passes.
“They turn a blind eye and let them in,” he said. “I know some in full uniform have gotten in, and also seen others turned away.”
The service is expected to conclude at 6pm UK time.
Where else are there memorials?
A memorial will also be held at the Flight 93 National Memorial in Pennsylvania.
The "September 11 Observance" is "free and open to the public," according to the National Park Service (NPS) website.
How to watch the memorials
The 9/11 memorial services in New York City and Pennsylvania will be broadcast live online by several major television networks.
NBC News, CNBC, ABC News, CBS News, Fox Business, and many others have previously live streamed the 9/11 commemorations on their YouTube channels.
The events are also expected to be broadcast through the "Watch Live" section of the 9/11 Memorial & Museum website, where the museum has live streamed other events.
What’s happening in the UK?
In the UK, the September 11 UK Families Support Group is holding a remembrance service at the September 11 Memorial Garden opposite the US embassy in London.
The service is a private event, and the garden will be closed to the public between 11am and 5pm. A minute’s silence will be observed at 1.46pm.
But after the private affairs have concluded, the garden will be opened to the public after sunset for a candlelight memorial which will stay open until 8pm.
“An installation of LED candles will be lit within the September 11 Memorial Garden in memory of all our loved ones that perished that day,” the support group says.
“We shall remember the lives of those taken, mourn the beautiful souls no longer with us and celebrate the love they brought into our lives.”
Will there be a minute’s silence?
While there is no “official” minute’s silence, many people choose to observe a moment of quiet contemplation at 1.46pm UK time, the moment the first plane struck the Twin Towers.
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