By the time the emergency services reached Sergei Skripal and his daughter, the pair were already frothing at the mouth, the whites of their eyes rolling in their heads.
Eyewitnesses had seen Yulia Skripal, 33, slumped on a bench, her father staring at the sky and making strange, contorted movements with his hands as the Sunday shoppers of Salisbury passed by. The Wiltshire city is more usually associated with its medieval cathedral or the neolithic remains at Stonehenge, which lie a few miles away across the vast chalk plain which covers much of south-west England.
But since the poisoning of Skripal and his daughter last Sunday, the city has become the focus of an attempted murder investigation and a symbol of the worsening relationship between Russia and the UK.
Sergei Viktorovich Skripal, a former colonel in Russian military intelligence, is believed to have begun working for MI6 in the mid-1990s.
Video footage which circulated widely last week shows him being put in a headlock and bundled into the back of an unmarked van when he was arrested in Moscow in 2004.
According to the prosecution case against him, which would lead to his eventual imprisonment, he passed state secrets to the British, including the identities of Russian spies.
In 2010 Skripal was released from prison along with three other Russian nationals jailed for espionage and pardoned as part of a spy exchange.
Vladimir Putin, himself a former KGB officer, was then serving as Russia’s prime minister, barred from a third consecutive term as president by the constitution.
In a TV interview at the time of the spy swap which has come to be interpreted as ominously prescient, Putin is reported to have said: “Traitors will kick the bucket. Trust me. These people betrayed their friends, their brothers in arms. Whatever they got in exchange for it, those 30 pieces of silver they were given, they will choke on them.”
But since his release from Russian custody, Skripal, 66, seems to have enjoyed the life of a happy retiree, unmolested by those associated with his former life. He lived in a modest home in a quiet cul-de-sac, shopping at his local convenience store for Polish sausage and scratchcards, and joining a local social club.
That period of apparent tranquillity came to a dramatic and violent end last weekend.
Skripal and Yulia, who is understood to work for PepsiCo in Moscow, are believed to have been in Salisbury city centre from around 1:30pm; witnesses reported seeing them in pizza restaurant Zizzi around 2pm.
Police would later seal off the restaurant and a nearby pub, The Mill, where the two Russians are believed to have also spent some time.
At 3:47pm they were caught walking side by side on CCTV, but by 4:15pm the emergency services had been alerted by concerned bystanders who saw Skripal and his daughter slumped on the bench outside The Maltings shopping centre.
By Tuesday, with the Skripals critically ill in hospital, Foreign Secretary Boris Johnson was making a direct link to the Kremlin, drawing comparisons with the assassination of Alexander Litvinenko in 2006 and warning of a “host of malign activity” by Russia.
Litvinenko, a former officer in the FSB intelligence agency who fled to Britain in 2000, died days after being poisoned with radioactive polonium-210, which he is believed to have drunk in a cup of tea during a meeting at a London sushi restaurant. A judge-led inquiry concluded he was the victim of a Russian state-backed assassination after Moscow refused to extradite the main suspect, Andrei Lugovoi.
Charles Bird, a former diplomat now based at St Andrews University’s Centre for the Study of Terrorism and Political Violence, says that while links to the Kremlin have yet to be established in the Skripal case, Litvinenko’s assassination shows Russia can act with impunity.
“One of the things the Russians will have done is a cost-benefit analysis,” he says. “They will have calculated that this is a former Russian spy who they are trying to knock off, if it is indeed proved to be the Russians.
“They will have asked what will the Brits do, what can the Brits do? A British court said they killed Litvinenko and Putin probably signed it off. Has it stopped them doing it again? No. Because they know they can do what they like. There’s very little that we can do in retaliation.”
Bird says the impact of British dignitaries boycotting this summer’s World Cup, as has been suggested by the foreign secretary, would be “utterly minimal”.
“We’ve already got sanctions on over Litvinenko, and over Crimea and Ukraine, and that hasn’t stopped them doing it again, if it is them behind it this time.
“They are facing international opprobrium over what they are doing in Syria and it hasn’t stopped them or had an impact.”
While Putin’s presidency has been marked by a souring of relations with the West, alleged interference in the American election and condemnation for his backing of Bashar al-Assad, he remains popular at home for restoring Russian pride following the chaos that came in the wake of the collapse of the Soviet Union and Boris Yeltsin’s years in charge.
The president, who has ruthlessly crushed dissent where it does exist, will win his fourth term in office when Russians go to the polls next Sunday. The result is not in doubt.
Alexei Navalny, an anti-corruption campaigner widely seen as the president’s most credible opponent, has been barred from standing. As the police investigation into the attack on the Skripals progressed last week, inquiries focused on establishing the source of the rare nerve agent used.
Sir Andrew Wood, a former British ambassador to Russia, says the apparent sophistication of the substance points to state involvement.
“I don’t see how it can be anything other,” he says. “There could be general powers delegated to the security services, but dangerous stuff like this would have to be given some sort of okay from the top. The Russians will always deny it, but there are not many people who have nerve gas. Something as sophisticated as this would only be in state hands and not every state would have it.”
That’s a view shared by Stephen Gethins MP, a member of the Foreign Affairs Committee who worked for NGOs in the former Soviet republic of Georgia and the Caucasus.
“It’s important for all of us to ascertain the facts about what happened as far as we possibly can,” he says. “I would hope that all authorities in the UK and elsewhere in world will help the police with their investigation as fully as possible. That said, we shouldn’t understate the seriousness of what has happened in Salisbury, where an attempted murder of a police officer and Mr Skripal and his daughter has taken place. It would be incredibly difficult to have carried out an attack of this nature without a great deal of preparation and perhaps even state involvement.
“For many years now, Russia has stepped outside what we consider to be international norms, even to the extent of annexing another state’s territory. The greatest victims of the Russian state’s activities are the Russian people themselves, who cannot rely on the protection of the rule of law or a government which violates the most basic human rights on the regular basis.”
Addressing MPs in the House of Commons last week, the Foreign Secretary said it was clear Russia is now “a malign and disruptive force” in the world. However, Johnson’s suggestion that British officials could chose not to attend the World Cup in Russia was met with derision in some quarters.
But Wood believes even symbolic gestures can have an impact.
“I don’t think there’s anything wrong with symbolic gestures. The Russians attach enormous importance to the World Cup, so it would be a slap in the face. I would have been tempted to do that anyway because of the way they are obliterating towns in Syria.
“But we need to talk to other Western powers, as this isn’t just an attack on the UK, but the West in general. If the Russians feel they are entitled and able to act this way here, they can do it anywhere.
“The only effect you can have on relations is a long-term one – I don’t think we have much choice.”
Russia has denied any involvement in the attack on the Skripals. Its embassy in London this week issued a strongly worded rebuke to the Foreign Secretary.
“Although absolutely no facts were provided to the public, we see the issue being translated into the domain of Russia-UK relations, with an active support by the media,” it said.
“The parliamentary debate as well as the government stance are a testament of London’s growing unpredictability as a partner in international relations, whose policy towards Russia is inconsistent and looks rather miscalculated, not least in the eyes of the Russian public.”
The gradual cooling of relations between London and Moscow under Putin has come in an era when a coterie of wealthy Russians have set up home in the English capital, bringing their billions with them.
It is this world which was recently dramatised in the BBC series McMafia, based on the non-fiction book of the same name by journalist Misha Glenny.
Its creators did not have far to look for real-life inspiration. In 2014, a coroner returned an open verdict following the death of oligarch and former Kremlin insider Boris Berezovsky.
Berezovsky, who lost a £3 billion damages claim against Chelsea FC owner Roman Abramovich two years earlier, had been suffering from depression and was said to have openly discussed suicide before being found on the bathroom floor of his Ascot home with a ligature around his neck.
The Home Office pathologist who carried out the post-mortem examination said there was nothing to suggest any other people were involved.
But Professor Bernd Brinkmann said there were indications Berezovsky had been strangled by someone else and then hanged from the shower rail.
In 2012, Alexander Perepilichnyy, 44, a commodity dealer who had been helping to investigate a money-laundering operation, collapsed and died while jogging near his Surrey home.
While initial toxicology tests revealed nothing suspicious and police found no evidence of foul play, the presence of a rare and deadly plant toxin was later found in Perepilichnyy’s stomach. An inquest into his death is continuing.
It was following the death of whistleblower Sergei Magnitsky, who died in a Russian prison in 2009, that authorities in the West decided to act.
Magnitsky, an auditor at a Moscow law firm, was detained in 2008 on suspicion of aiding tax evasion after reporting a tax fraud involving Russian officials and police officers. He died in custody in 2009 at the age of 37 from acute heart failure and toxic shock caused by untreated pancreatitis.
His death inspired the Magnitsky Act in the United States which promised to deny visas to and freeze assets in the US of 18 people linked to the lawyer’s death.
Partly in response to the American legislation, the UK Criminal Finances Act came into law last year with the power to freeze the assets of foreign officials under Unexplained Wealth Orders.
Last month the National Crime Agency (NCA) secured the first two such orders in relation to assets totalling £22 million which it said it believed are owned by a “politically exposed person”.
The orders relate to two properties, one in London and the other in the south-east of England.
As the criminal investigation into the attack on the Skripals progressed last week, the bench where the two Russians took ill remained covered by a police forensics tent.
When wind threatened to dislodge it at one point on Thursday, men wearing bright yellow hazmat suits moved in to secure it once more.
Military personnel were deployed to the streets of Salisbury to aid the investigation as the first police officer on the scene, Detective Sergeant Nick Bailey, continued his recovery in hospital.
While the police investigation looks set to take some time, the diplomatic fallout could last for years.
“They’ll go through all the usual hoops, chucking out the ambassador and the declared intelligence officers,” says Bird.
“But Putin thinks long term: he’s faced down the West, Nato and the UN over Crimea, Ukraine and Syria; he’s got away with Litvinenko. The reality is that there’s very little that can be done to stop him.”