Alexander Litvinenko is believed to be the first known person to have died as a result of being administered a lethal radioactive cocktail of polonium 210.

Investigators reckon it may have been smuggled into Britain. It can easily be carried around in a bottle without any risk, yet it is 250 billion times deadlier than cyanide and a particle the size of a speck of dust is all that is needed to kill someone.

The most likely method would be to slip it into someone’s drink or sprinkle it on their food to ensure it was digested, killing off each of the internal organs.

As we know from Alexander, it was not an instant death, but slow and agonising, despite being a billion times more radioactive than uranium.

The only known use for polonium 210 is in nuclear bomb triggers and as a heat or power source in satellites and moon buggies.

Polonium 210 is a most desirable weapon for terrorists who could easily smuggle it through our airports in an inconspicuous looking bottle. It could have terrifying consequences if terrorists administered it to our water system. I fear this is the weapon of the future that we should fear due to the ease with which it can escape detection and airport security, that it is visibly insignificant – yet could cause the most horrific death tolls.  How do we protect ourselves against this weapon of mass destruction?