Here in my eyrie in Wapping I look down on a small, well-kept park. It is a favourite picnic spot for families who gather on the grass when the sun shines. But in the corner, behind some bushes, in a spot invisible to the families, is the addicts’ den.

The smack addicts come to inject, the crackheads to smoke. I noticed the crack fans first, but had to google the words “crack” and “bowels” to interpret the scene. It seems that, as if it were not enough that crack turns you into a sub-human moron, it also makes you lose control of your bowels. Ah, the glamour, the showbiz razzmatazz of the drugs world.

It is painfully, patently, obvious that the war on drugs has been lost. Napoleon’s outing at Waterloo looks like victory on points compared to our campaign against drugs. There has been no one big, definitive battle to allow a declaration of total defeat: just millions of small, lost battlefields, like the one I can see as I type, littered with used needles and unrealised dreams; spattered with faeces and blood.

The victims of this lost war are everywhere. There are those who choose to be victims, like the kids who gather in a slow, sad suicide pact in the bush opposite me. Then there are are the collateral victims: those that the junkies rob to fund their habits, the children trafficked to work on the UK’s cannabis farms. There are 11,000 dead Mexicans on the front line, whose Government’s fraught drugs offensive is tipping the country into failed-state territory. There are the “$10 tabies”, as they are dubbed by the US military — the Afghans who support the Taleban for a share of the $400 million a year opium trade. There are the British and American soldiers killed by weapons bought by opium dollars.

The list could go on for ever.

The demand is constant, the supply uninterrupted. A report yesterday from the UK Drug Policy Commission, an independent body, came to the stark conclusion that trying to reduce supply by enforcement of the law has little or no impact. The drugs market, the report says, is “large, resilient and quick to adapt”. Arrest a dealer, and another appears. But our attempts to slay this modern Hydra lead to more problems; turf wars and violence. The report concludes that the police should target their resources more effectively: ignore the low-level dealers and concentrate on the harm caused by the market.

But the report does not go far enough. The harm caused by the drugs market derives both from its existence and its illegality. We have tried and failed to do something about the former; it is time to tackle the latter. Drugs must be legal and licensed, like alcohol. Not decriminalised, the fudge policy of the defeated, but legalised.

Those who want to take drugs should be able to walk into a shop and order a pill from the blue jar, or a powder from the red, like a chemist crossed with a sweetie shop. Free, clean needles should be available; two free with every bag of heroin!

The market must come out of the darkness. It must be made a headache for the Revenue bit of Her Majesty’s Revenue & Customs, leaving the Customs bit to deal with the odd bootlegged stash. The economics of legalisation suggest that consumption would rise initially. Prohibition makes drugs expensive; the risk of illegal production and distribution is built into the price. Cheaper drugs are likely to lead to higher use; there is a correlation between street price and which drugs land users in hospital emergency rooms.

But price matters to those already embroiled in drugs. Would it make a difference to the unconverted? Would anyone not already immersed in the culture seriously choose an evening’s entertainment based on the relative price of smack versus a pint?

The present system does even less for addicts than for collateral victims. They are thrown on to methadone and abandoned. Licensed, regulated and taxed, there could be a hypothecated revenue from drugs to pay for rehabilitation and life creation. Life as an ex-junkie can be even worse than life as a junkie.

The Gateway theory, which suggests that teenagers start on cheap cider and fags, graduate on to Ecstasy by way of pot, and end up injecting smack into their eyeballs, has been debunked. The Advisory Council on the Misuse of Drugs found no convincing evidence of a causal chain, linking cider in a bus stop with smack in a burger bar toilet. Any teenager can stop at any point in the chain. Whether or not drugs are legal is irrelevant. But the illegality of drugs means that every teenager who smokes pot is exposed to a dealer who has a vested interest in making him an addict.

There is already a horrifyingly casual attitude to recreational drug use in Britain. I am one of the only people I know who has never popped a pill or used cocaine. Legalisation could not make drugs much more ubiquitous than they already are.

All drugs are dangerous. As I walk my daughter to her nursery in the morning, we see the alkies and the junkies split in tribal groupings. The alkies are as toothless and grubby as the junkies, although more cheerful at that time of the morning — the first few cans have taken the edge off. My greatest fear is that my daughter will choose to join their zombie-ish ranks; the legal status of drugs makes no difference at all as to how likely that is.

The main difference between the tribes is that the alkies surrender their souls to Special Brew sitting on the grass. The junkies hide in the bushes. Legalisation could draw them out. But this would be an effective deterrent. The likes of Pete Doherty have a kind of doomed glamour in a photograph. Close up and shooting up, there’s no glamour at all; only revulsion and pity.

By legalising, we would have a fighting chance of wresting the market from the hands of the drug barons: the ones who ruin lives and distort global politics and are untouched by our laughable efforts to police them. They are the only winners in the current futile war.

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