Cannabis and hippies are synonymous with one another, joined at the hip in the history books and in popular culture, with a spliff never far from the mouth of a long-haired, bespectacled CND campaigner. But the drug inhaled by the free-living spirits of the 60s and 70s was 14 per cent weaker than what is dealt on the world's streets today, a study has found. For cannabis resin, or hash ...