Whilst most Britons would cite Sir Walter Raleigh as responsible for introducing the evil weed to England, the first recorded reference to tobacco is due to Columbus in 1492. On his voyage to Cuba he discovers "men with half-burned wood in their hands and certain herbs to take their smokes". He also recollects those smoking it saying "they were unable to cease using it". So addiction is evident right from the beginning.   It would take to the 1950s to work out how this addiction harmed health with Doll & Hill's study on doctors and lung cancer and by now it's all pervasive and anti-smoking agencies have been running to catch up with the habit ever since.   So where in London can we take a 'smoking' tour? Raleigh is with us in Greenwich and St Margaret's Church, Westminster - his statue is easy to find in the former but you have to search out his burial place in the latter. Tavistock Square has the British Medical Journal which published the first findings on health effects and next door was the home of the Health Education Council whose campaigns have dramatically cut smoking numbers.   For one of those lovely London links head for Temple Station to find the HQ of British American Tobacco next to Two Temple Place. Look carefully at its weathervane and you'll see it's the model of the Santa Maria which carried Columbus on his voyage to the Americas.   And to complete the journey it's off to Belgrave Square where we'll find a statue of the explorer himself, seated, relaxed, pointing with his papers - and not a cigarette in sight.