Here is a link for British drug prohibition and history
http://www.drugtext.org/library/articles/five2.html
Just an excerpt
In Colombia, and in several other Latin American and Caribbean countries, the cocaine traders are a least as powerful as the Government. The resulting instability is a real threat to feedom, not to mention world trade and investment. The threat is growing fast. It is, I repeat illegality - and the failure of prohibition -that gives the traders their untaxed wealth, power and guns.
1838 FIRST OPIUMWAR BETWEEN CHINA AND BRITAIN UK foists Indian opium on unwilling Imperial administration.
1868 PHARMACY AND POISONS ACT. Opium and later morphine sale restricted to pharmacists.
1909 SHANGHAI OPIUM COMMISSION Non-binding international agreement aimed at curbing UK opium trafficking and restricting opiates to medical use.
1912 FIRST OPIUM CONVENTION (HAGUE CONVENTION) International treaty committing signatories to pharmacy laws to restrict opiates and cocaine to medical use.
1916 DEFENCE OF THE REALM ACT REGULATION 408. Emergency regulations banning opium or cocaine possession or supply without prescription in response to cocaine epidemic among soldiers.
1917 ENQUIRY INTO COCAINE USE IN DENTISTRY Concluded there was no noticable cocaine problem.
1918 TREATY ENDING FIRST WORLD WAR Ratification of Hague Convention mandatory.
1920 FIRST DANGEROUS DRUGS ACT AND LATER REGULATION Implemented Hague Convention in UK making it a criminal offence to posses opiates or cocaine without prescription.
1925 GENEVA CONVENTION International treaty extending control to cannabis.
1925 DANGEROUS DRUG ACT. Implemented Geneva Convention in UK, extending 1920 Act to cannabis and coca leaves.
1926 ROLLESTON REPORT. Established that indefinite (maintenance) prescribing was a legitimate medical response to opiate addiction in Britain.
1961 UN SINGLE CONVENTION ON NARCOTIC DRUGS Cornerstone international treaty consolidating and extending earlier conventions.
1960S YOUTH REVOLUTION Doctors lose control of spread of addiction; cannabis, stimulants and hallucinogens join youth pharmacopeia.
1964 DRUGS (PREVENTION OF MISUSE) ACT. Controlled amphetamines in UK in advance of international agreements; later used to control LSD.
1965 SECOND BRAIN REPORT. Concluded growth of addiction in UK required heroin and cocaine prescribing to addicts to be limited to licensed doctors in clinics.
1967 DANGEROUS DRUG ACT. Implemented Second Brain Report.
1969 WOOTTON REPORT. Official UK government advisory body said no one should be imprisoned for possessing cannabis and recommends penalty reductions. Advice rejected.
1971 UN CONVENTION ON PSYCHOTROPIC SUBSTANCES Extends international controls to synthetic drugs including amphetamines and LSD.
1971 MISUSE OF DRUGS ACT. Cornerstone of UK legislation consolidating and extending earlier acts.
1973 MISUSE OF DRUGS ACT COMES INTO FORCE.
1986 DRUG TRAFFICKING OFFENCES ACT. UK law requiring confiscation of assets of convicted drug traffickers widely seen as reversing burden of proof. Also banned the supply of drug paraphernalia except
1988 UN CONVENTION AGAINST ILLICIT TRAFFIC IN NARCOTIC AND PSYCHOTROPIC SUBSTANCES. Increased sanctions and powers in respect of seizure and confiscation of assets, extradition and other enforcement