On July 26, 1963, passengers boarded a Northern Line tube train at Morden in South London heading for the City. Their short journey to work, perhaps to London Bridge or Bank, seemed the same as any other day. But it was far from ordinary.
What those passengers did not know – could not know – was they were an unwitting cast of extras in a secret experiment conducted by government scientists from Porton Down, headquarters for the country’s military research since 1916.
As the train wound northwards through the dark tunnels between Colliers Wood and Tooting Broadway, a window was opened and a scented powder puff was thrown out on to the tracks below. This particular powder puff contained not cosmetics but freeze-dried spores from the anthrax family, B globigii bacteria, which can cause eye infections, food poisoning and, more serious still, septicaemia, the cause of deadly sepsis.
The Northern Line was chosen because, at 17 miles, the line heading north is the longest tunnelled section on the London Underground, ensuring the spores now wafting along it were trapped, unable to disperse in the wind.
Pushed and pulled along the system by passing trains, the spores took 15 minutes to travel ten miles to Camden Town, contaminating all stops on the way.
There is no record of precisely why this reckless operation took place, although it was doubtless to gauge the behaviour of biological weapons in the event of an enemy attack. It was certainly important enough to be repeated on the same stretch of the Underground a year later.