"Wall Street got drunk" was George W Bush's typically incisive take on the main cause of the emerging financial crisis in July 2008. Two years later the governor of the Bank of England, Mervyn King, explained in his Mansion House speech that "the role of a central bank in monetary policy is to take the punch bowl away just as the party gets going" (something that he admitted had not occurred). But perhaps the wrong intoxicant was being blamed. The controversial former drug tsar David Nutt told the Sunday Times this weekend that cocaine-using bankers with their "culture of excitement and drive and more and more and more ... got us into this terrible mess".

I'm inclined to agree. Cocaine is (I'm reliably informed) a drug that results in intense bouts of over-exuberance as well as a tendency to talk extremely convincingly about stuff you know nothing about. Everyone accepts that a credit bubble occurred in the mid-noughties and that it was a direct result of what the former US Federal Reserve chief Alan Greenspan has referred to as "irrational exuberance". It could also be argued that traders would be better able to sell absurdly complicated financial weapons of mass destruction after taking a confidence-boosting narcotic such as cocaine. Furthermore, surely only cocaine-ravaged buffoons would actually buy billions of dollars worth of mortgage-backed securities when they were so clearly doomed to explode the minute the property boom stalled.

I certainly saw my fair share of sniffly noses and gurning jaws at City bars every Thursday night. I also heard overconfident gibberish being spouted by brash wide-boys throughout my 12-year banking career. There were also lots of stories about some of the big swingers in New York enjoying a line or 10 of an evening. Bernie Madoff's office was apparently known as "the North Pole" such were the gargantuan quantities of "snow" to be found there and most bankers are aware of the published allegations that Jimmy Cayne (former CEO of Bear Stearns) had an anti-acid medication bottle that was filled with cocaine.

Dr Chris Luke, an A&E specialist based at Cork University Hospital, Ireland, who has studied the effects of cocaine on bankers, has stated that "prominent figures in financial and political circles made irrational decisions as a result of megalomania brought on by cocaine usage". He concludes that "people were making insane decisions and thinking they were 110% right … which led to the current chaos."

Greed, selfishness, ignorance and ruthlessness also played their part, of course, but I think it would be foolish not to see the role that the drug played in creating the bubble. Herd mentality, which thrives during times of uncertainty, is certainly much more explicable when you factor in the trembling insecurity and depleted discernment that go hand in hand with a coke habit.

There is, I'm pleased to say, a happy ending to this sorry tale: my ex-colleagues and clients who still work in the Square Mile tell me that many City boys are now too scared to keep snorting the Bolivian marching powder. This may mean bankers are having less fun but, surely, it can only lead to a more restrained and sensible financial system.

@cityboylondon