It will have been without question one of the strangest periods of her reign. After 220 days working behind the closed doors of palaces and castles, the Queen's Covid-19 isolation came to an end today, as she stepped out for the first time since March.
The Queen, joined by the Duke of Cambridge, braved the re-emerging threat of coronavirus to fulfil her commitment to staff at the UK's national security laboratory at Porton Down, Salisbury.
Without masks, they heard of work to battle Covid-19 as well as ongoing counter terrorism and the rapid response to 2018's Novichok poisoning attack.
From afar, it was as if she had never been away, as the Queen returned to what she does best: meeting her public, thanking unsung heroes and unveiling a plaque for good measure.
In a rose-coloured Stewart Parvin outfit, with her trusty handbag and hat, she beamed at Defence Science and Technology Laboratory (Dstl) staff waiting to meet her, having scoured the site in preparation for their VIP visitor.
But anyone paying close attention to photographs would notice the small but extraordinary details which allowed it to happen, even as much of the UK plunges into a new era of Covid-19 measures.
Porton Down hosts walked a careful social distance from the Queen at all times, with even the Duke giving his 94-year-old grandmother a careful wide berth as they toured the site.
Floor markings dictated where people could stand without putting their visitor at heightened risk, with hand sanitiser at every corner.
All 48 members of staff had been tested "very recently" for Covid-19, a source said, granted permission to attend the event only with the confirmation of a negative test made possible by the on-site expertise and facilities to turn them around quickly.
A small number of others - including select members of the press - were kept well back and in facemasks.
The visit was designed carefully, with a specially-built, open-sided marquee for meeting and greeting, and a demonstration of how they use dogs to detect explosives in a similarly well-aired hangar.
The Queen arrived by deep-cleaned helicopter from Windsor Castle, while the Duke travelled separately by car.
Although Kensington Palace declined to confirm citing privacy, it is understood that the Duke - who has two children at primary school - had also tested negative for Covid-19.
He is believed to have last seen his grandmother during a family stay at Balmoral this summer, when the Cambridge family joined the Queen and Duke of Edinburgh for their traditional annual countryside retreat.
Given the precautions, royal household doctors felt it was safe for the Queen to go without her own mask, allowing her to make conversation and complete the job she was setting out to do unencumbered.
A Buckingham Palace spokesman said: "Specific advice has been sought from the medical household and relevant parties, and all necessary precautions taken, working closely with Dstl."
It was a cautious re-entry for the Queen into the world of public engagements, as her aides work to protect her from catching coronavirus and further unsettling a country already facing deep challenges.
Until now, she has been protected in a carefully-choreographed model nicknamed HMS Bubble and enabled by a close-knit team prepared to isolate at Windsor Castle and then Balmoral.
From mid-March, the Queen and Duke of Edinburgh lived in their private apartments at Windsor assisted by 22 members of staff who worked in a three-week rotation away from their own families.
Over the summer, they moved a make-shift court to Balmoral, but returned to Sandringham earlier than expected for a short break at Wood Farm before the Queen returned to work at Windsor earlier this month.
Though she has never been far from television screen and newspapers through the pandemic, with special addresses and a plethora of video calls to charities to help rally people through lockdown, it is understood that the Queen has been keen to get back to normal business as soon as was feasible.
The Porton Down trip had originally been scheduled for April, postponed through necessity.
But several weeks ago, the palace decided it was possible to go ahead, in what was intended as a very visible "back to work" message from the top.
This week, as rising numbers of coronavirus cases loomed and a new "tier" lockdown system was introduced, the Queen and Duke remained committed to fulfilling their promise.
A source said: "Although virtual engagements have proven popular at recognising the invaluable work done by many individuals and organisations, being out and about just feels a better way to create memories for people that will last forever and be passed down through generations."
Future engagements will be considered on a day-by-day basis, it is understood, balancing duty and government guidance, as well as setting an example of calm leadership.
The Duke and Duchess of Cambridge have already made a gradual return to in-person engagements, along with the Duchess of Cornwall and Prince of Wales, who contracted coronavirus in March.
Seven months after the Commonwealth Day Service at Westminster Abbey, her last major appearance in public, the Queen yesterday left lockdown in fine fashion, from questioning why she had to get into her Bentley instead of making the short walk from her helicopter to joking that she'd signed the guest book so "it proves we've been here, doesn't it?".
Joined by her grandson the Duke, they pair privately viewed the Linear Accelerator (Linac), used for inspecting weapons and munitions, and watched an explosive-detection scenario with sniffer dog Max.
"Is he more interested in the ball or the explosives?" the Queen asked, smiling knowingly when told: "Always the ball!".
Meeting staff who had helped with the UK's Covid response, including Professor Tim Atkins, the Queen remarked of the virus: "It's doubling itself again".
Told that it was and "we will have to evaluate how we approach this", she added: "Well I suppose it was expected?"
Atkins said: "Predicted ma'am, yes."
"With all these horrible new things..." she said.
"Absolutely, it's an emerging new disease" said Atkins.
At the end of the visit, the Queen and Duke unveiled a commemorative plaque officially opening the new £30million ($58m) Energetics Analysis Centre.
The Duke presented the Firmin Sword of Peace to Colonel Mike Duff, on behalf of the Army's Headquarters South West in recognition of all the support it gave to the city of Salisbury after the Novichok attack in March 2018.
After the 50-minute visit, the Duke stayed on at Porton Down to view the Air Force's newest fast jet, the F35.
Gary Aitkenhead, chief executive, said: "People have such passion and commitment, during the pandemic everyone wanted to come in to work in order to help the national effort.
"It was fantastic the Queen and Duke could come here today, safely, and recognise that."
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