Hospital staff who saved the lives of poisoned Russians Sergei and Yulia Skripal have revealed they did not expect the victims of the nerve agent attack to survive.
The Skripals had been found slumped on a bench on 4 March - but staff treating them at Salisbury District Hospital did not initially know the reason why.
Nursing director Lorna Wilkinson said a key moment came when policeman Nick Bailey was admitted with similar symptoms. "There was a real concern as to how big this could get," she said.
She told BBC: "Have we just gone from having two index patients having something that actually could become all-consuming and involve many casualties? Because we really didn't know at that point."
And ward sister Sarah Clark, who was on duty that night, added that there were fears that the hospital's staff might end up being affected.
She pointed out that they had not, at that stage, "taken any extra precautions in terms of protecting ourselves".
When the nature of what they were facing became clear, hospital staff said they did not have high hopes of ever seeing their two patients recover.
But after weeks of treatment - involving expert advice from the nearby Porton Down research facility - Yulia and then Sergei were eventually discharged to continue their recovery at an undisclosed address.
The series of interviews with Newsnight marks the first time that staff at the hospital have spoken in detail about the event and how they reacted.
'Wildest imagination'
The testimonies of the medical staff highlight the vital importance of the decisions made at key times: the speedy arrival in intensive care, the heavy sedation used to limit possible brain damage, and the importance of advice, tests and treatments suggested by the Porton Down experts.
When the Skripals were found, an opioid overdose was suspected.
"We were just told that there were two patients down in the emergency department who were critically unwell and they would be coming up to the unit," recalled ward sister Ms Clark.
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But when police became aware of Mr Skripal's former career as a Russian spy, they told the hospital and discussed the possibility that he may have been the victim of a targeted attack.
A major incident was declared at the hospital and police moved in to protect the Skripals.
"I spoke to the nurse in charge," recalled Dr Duncan Murray, the hospital's senior intensive care consultant, "and it was this conversation I really could never have imagined in my wildest imagination as having with anyone...
"Essentially the story of a known Russian spy having been admitted to hospital in pretty unusual circumstances."