- The incredible footage, exclusively obtained by MailOnline, shows the two men strolling through Salisbury
- It was taken shortly after 1pm on Sunday March 4 just minutes after the Russian spies had sprayed the Skripals' doorknob with novichok
- Russian pair looked like they didn't have a care in the world as they wandered past Dauwalders collectables
- Something in the shop's vintage coin display caught Alexander Petrov's eye and he stopped fellow assassin Ruslan Boshirov
- The pair then spend several moments examining the shop window before appearing to try and go inside - then realising it was closed
- This all happened just a few minutes before the pair were filmed arriving at Salisbury railway station to board a train on their way to Heathrow Airport
This is the astonishing moment the two Russian novichok assassins casually window-shopped in Salisbury just minutes after they tried to murder former double agent Sergei Skripal and his daughter.
The first footage seen of the killers, obtained exclusively by MailOnline, shows the two men looking relaxed and good-humoured as they sauntered down the street towards Salisbury station to make their getaway.
Dressed in winter clothing, Alexander Petrov and Ruslan Boshirov are seen walking past the Dauwalders collectables and rare stamp shop before becoming distracted by the window display.
Petrov is wearing a backpack, black woolly hat and blue down coat, while Boshirov is wearing a dark bomber jacket and a baseball cap.
Appearing to forget about their mission, they examine the window display in detail, talking enthusiastically about the collectors' items.
They then approach the shop entrance as if to make a purchase, before realising that the shop is closed and continued towards Salisbury railway station and make their escape.
The assassins were looking at a collection of old coins in the window, the shopkeepers confirmed.
Paul Dauwalder, who owns the well-known business, said: 'They seemed quite bungling, to be honest. The coins aren't the valuable ones, we wouldn't keep them in the window.
'It's an ongoing window display that often attracts attention. There are some foreign coins, Victorian pennies, that sort of thing. Maybe they were looking for Russian ones.
'It was a Sunday and they had just attempted a murder, but they still tried to come in the shop. They were obviously coin fans.
'They might be murderers but that doesn't mean they are intellectually dead. From the way they were behaving, they looked like coin enthusiasts or collectors.
'People often spend hours going through those boxes of coins. It's not unusual. It seems we even attract Russian murderers.'
Dauwalders of Salisbury is a family-owned business selling rare stamps and other collectables to both retail and wholesale customers.
Set up in 1958, it is run by a father-and-son team, Paul and Chris Dauwalder. In addition to rare stamps, it offers unusual coins, posters and philatelical accessories.
Paul's son, Chris, 28, said: 'There is no danger of contamination as they didn't come into the shop. We have a window cleaner once a week and he's still alright, so it's probably safe.'
'They looked like ordinary guys,' Paul added. 'If it had been mid-week and we were open, they would have come into the shop and we would have served them.
'The mind boggles. I'm just glad we were closed.'
The exclusive footage provides an insight into the relaxed mindset of the two assassins – who the Prime Minister has said worked for Russia's GRU military intelligence service – just minutes after they carried out attempted murder.
While the pair window-shopped, former spy Skripal and his daughter Yulia were just hours away from becoming hospitalised, in a chain of events that would lead to the death of drug addict Dawn Sturgess, 44, and a new low in relations between Russia and Britain.
By the following day the killers would be back in Russia while police frantically sealed off contaminated parts of Salisbury and the manhunt began.
It would be a further six months before their identities would finally be made public by the British authorities.
It comes as Britain's security minister today said Russian President Vladimir Putin bears ultimate responsibility for the Novichok nerve agent attack carried out in England.
Britain has vowed to wreak revenge on the Russian President by ordering a covert war as the Prime Minister accused two of his agents of carrying out the mission in March.
Security Minister Ben Wallace said today he is '100 per cent sure' the men named carried out the attack and claimed that Vladimir Putin has ultimate responsibility for the actions of his spies - but added: 'This was more Johnny English than James Bond'.
He said: 'Ultimately he does, insofar as he is president of the Russian Federation and it is his government that controls, funds and directs the military intelligence - that's the GRU - via his minister of defence. I don't think that anyone can ever say that Mr Putin isn't in control of his state'.
He added: 'They [the assassins] are members of the GRU - this is not some rogue or some freelance operation. Soldiers do as they told, they take orders. So I think it's very clear that the Russian state bears significant amounts of responsibility for this, alongside individuals who have chosen to attack British citizens and people in this country'.
When asked how the UK would respond he refused to say, adding: 'We retaliate in our way. We are not the Russians, we don't adopt the sort of thuggish, destructive and aggressive behaviour that we have seen. We choose to challenge the Russians in both the overt and the covert space, within the rule of law and in a sophisticated way'.
The Security Minister also revealed how the security services know the Russian state must have helped the get to Britain while carrying the deadly nerve agent.
The assassins were travelling on genuine Russian passports, using credible aliases and transporting novichok, which was designed and produced by the state, in a perfume bottle with sophisticated technology to stop it leaking and a nozzle to help them use the deadly weapon.
Theresa May will wreak revenge on Russia with cyber warfare, espionage, financial sanctions and travel bans all likely to be used, sources said.
Interpol has been put on red alert to detain the two agents, who use the aliases Alexander Petrov and Ruslan Boshirov.
Mrs May has warned they would be brought to Britain for trial if they ever left Russia - but experts have said that Vladimir Putin will personally ensure the assassins never leave the country and reward them with lucrative promotions despite botching their assassination attempt on Sergei Skripal and his daughter Yulia.
However, she did acknowledge that it was futile to expect Russia to hand over the two assassins, not least because Russia has a constitutional bar on extradition.
She savaged Moscow's response to the novichok attacks, saying requests for co-operation had been met with 'obfuscation and lies'.
MPs were told new powers were in force to stop at the border anyone suspected of 'hostile state activity'.
Russian oligarchs linked to Mr Putin face a clampdown, including searches of private flights and investigations of 'unexplained wealth' by the National Crime Agency.
Mrs May said retaliatory action would focus specifically against the GRU, the organisation linked to the downing of the MH17 airliner in Ukraine, attacks in Syria and election-rigging in the United States. She said it was clear the Salisbury attack was not a rogue operation and must have been approved at a senior level of the Russian state.
Investigators believe they know the identities of the two military intelligence agents but chose instead to publicise aliases used in their Russian passports.
They are asking people worldwide to contact them if they can put a name to the faces. Police obtained domestic and European arrest warrants, and lodged Interpol red notices, effectively confining the pair to their homeland.
But the Crown Prosecution Service said it would not apply for their extradition because the Russian State refuses to deport its citizens to face trial overseas.
Both men are believed to be agents for the GRU, for whom Mr Skripal was a colonel before being jailed for selling secrets to the West. He was brought to the UK in a spy swap.
In a bid to silence the chorus of online scepticism about the case fuelled by Russian trolls, police gave a step-by-step account of the movements of the two-man hit squad.
CCTV stills showed Petrov and Boshirov arriving at Gatwick Friday on March 2 on an Aeroflot flight from Moscow, before catching a train to London Victoria.
They then travelled to London Waterloo where they were seen between 6 and 7pm before checking into the budget City Stay Hotel in Bow Road, East London.
Dressed in padded jackets, hats and carrying a rucksack, the following day the pair left their hotel at 11am and caught the tube back to Waterloo to jump on the London to Salisbury train which arrived in the cathedral city at 2.25pm.
There they did what police believe was a reconnaissance of the Salisbury area, before catching a train back to London at 4.10pm and checking back into their Bow hotel at 8.05pm.
On the Sunday, they left their hotel at 8am, again taking the tube to Waterloo where they caught another train to Salisbury, arriving back in the city shortly before midday.
CCTV showed the two men close to the Skripals' house at 11.58am and walking through the streets of the city between 1 and 2pm.
The men caught a train back to London around 2pm and arrived back at Waterloo at 4.45pm, then caught a tube to Heathrow airport at 6.30pm.
Little more than 48 hours after they arrived in the UK, Petrov and Boshirov caught the 10.30pm flight back to Moscow, just over 50 hours after first touching down.
It is understood that the 250-strong team of detectives identified the two men as suspects in May while examining more than 11,000 hours of footage.
They were able to painstakingly follow their steps, leading to the City Stay Hotel, in Bow, east London, where they spent both nights. Forensics experts discovered a minute trace of novichok in their room, a sample so small it was washed away by the testing swab.