What political leaders of ours have not dabbled in drugs over the years? It might be cold comfort to David Cameron, but the problem seems to touch politicians irrespective of party.
Past prime ministers who these days would instantly earn an Asbo include William Pitt the Younger, who ended one magisterial drinking binge by jumping the barrier at a turnpike road, thus cheating the toll, and only narrowly cheating death when the gatekeeper shot at him with a blunderbuss. Pitt was, in fact, following unlikely-sounding doctor's advice to drink a bottle of port each day - a prescription to which he more than adhered. Charles James Fox was equally Bacchic; his autopsy described his liver as "preternaturally hard" and "almost entirely schirrous".
When Marx wrote that religion was the opium of the people it may have been a hint that the ruling classes stuck to the real thing, and indeed William Wilberforce and William Gladstone were both users. Gladstone used to spice his coffee with laudanum (opium dissolved in alcohol)
before parliamentary speeches, in order to calm his nerves and enhance his delivery.
Gladstone's successor as prime minister, Lord Rosebery, took sulphonal to ease his chronic insomnia, which had brought him to the point of nervous and physical collapse. He later apparently took cocaine - then legal - to add zest to his speeches.
A generation on, Benzedrine was the drug of choice in high society. The Tory MP and diarist "Chips" Channon described his preparations for hosting a soiree: "I 'laced' the cocktails with Benzedrine, which I find always makes a party go." Anthony Eden admitted he was practically living on Benzedrine during his unhinged management of the Suez affair.
The substance of first resort for abuse, though, remained alcohol. Winston Churchill, that most heroic of drinkers, said late in life that he had always taken more out of alcohol than alcohol had taken out of him. A counter-example was the 1960s cabinet minister George Brown (for whom Private Eye coined the euphemism "tired and emotional"), whose drink problem helped disqualify him from the Labour Party leadership after the death of Hugh Gaitskell.
At least 30 current MPs have admitted using illegal soft drugs in the past, including the Tory party chairman Francis Maude and the Home Secretary, Charles Clarke. And cannabis use has prompted politicians to their most cringe-worthy extenuations. Bill Clinton famously admitted smoking dope, but not inhaling, while Newt Gingrich's excuse could be taught as a lesson in how drugs damage the brain: "When I smoked pot it was illegal, but not immoral. Now it is illegal and immoral. The law didn't change, only the morality. That's why you get to go to jail and I don't."
America was also home to the politician with the most generous cocktail of chemicals. John F Kennedy was already taking large doses of steroids and amphetamines when one of his mistresses introduced him to marijuana.
Finally, there are the significant silences: George W Bush's full drug record, like Cameron's, remains unclear - as, indeed, does Tony Blair's.