Last week, it was revealed that the Russian opposition politician Alexei Navalny had been poisoned by Novichok. The revelation brought back memories of two years ago, when the same nerve agent was used on the streets of Salisbury.

‘It churns it all up again,’ Dawn Sturgess’ father Stan told The Guardian. Nick Bailey’s wife Sara responded to Boris Johnson’s calling the attack ‘outrageous’ by tweeting ‘actions speak louder than words.’

Someone else who knows the terrible danger of chemical weapons is Hamish de Bretton-Gordon. Hamish, whose fascinating memoir Chemical Warrior, was published last week, spent over two decades in the army, where he served as Commanding Officer of the Chemical, Biological, Radiological and Nuclear Regiment (CBRN).

He went on to co-found humanitarian group Doctors Under Fire and continues to advise the government on biological warfare.

Hamish’s book is an intriguing mix of a remarkable career, chemical weapons history, and more personal reflections. I caught up with him last week and asked how we reached the point of the Skripal and Navalny attacks.

For Hamish, the timeline can be traced back to Syria in 2013, where President Assad used Sarin in a rocket attack on opposition areas. That was the moment, Hamish explained, that the ‘red line’ was crossed, and the world failed to respond.

As for Russia, Hamish said that Putin ‘just doesn’t care about collateral damage’. And while it might be cold comfort to Dawn Sturgess’ family, he claimed, ‘Salisbury got away with it’ – thousands, potentially, could have been killed.

I asked Hamish about the forthcoming inquest into Dawn’s death, whose scope the High Court ruled must be widened. In his book, Hamish mentions ‘many in the intelligence community’ believe that the perfume bottle picked up by Dawn and Charlie Rowley was not the one used in the original attack.

Hamish quoted Donald Rumsfeld’s line about known knowns and known unknowns: despite his connections, he said he wasn’t aware of much information not already in the public domain. Many of the family’s questions about the attack, he cautioned, may never be answered.

The Skripal attack was far from the only possible Russian attack on British soil. Hamish’s book mentions the allegations surrounding fourteen other Russians who have also died in the UK in recent years, all in suspicious circumstances.

His book also notes the ‘mysterious’ death of scientist Vladimir Pasechnik. Pasechnik was an important figure in expanding the Soviet Union’s biological weapons programme, before his defection to the UK in 1989.

The information he brought with him, described by Hamish as ‘gold dust’, revealed that the Soviets’ germ warfare capability was ten times greater than believed. Pasechnik then worked at Porton Down for a decade, before his death in Salisbury in 2001.

Following the attack on the Skripals, Pasechnik’s son Nikita asked the government to look again at his father’s death. Officially classed as a stroke, Nikita told the Daily Mirror how doctors said of his father that, ‘his brain was severely damaged in different areas … they had never seen a stroke like it – it was as if he had several strokes simultaneously.’

I asked Hamish how likely it was that the Skripals weren’t the first Russians to be attacked in Salisbury. ‘It wouldn’t be beyond the bounds of possibility,’ he replied.