Fags are designed so that about three quarters to an hour after you have smoked one, your drug levels reduce and create a craving for another one. It is this process that creates the pack of 20, because that is about how many a normal smoker will smoke in a day if in response to their reduced nicotine levels they do light up another fag.
Normal smokers will smoke 20 a day whatever the price as long as it is affordable. So Government pricing a pack at £6.00 just generates that amount of revenue for the taxman, it won't have an effect on consumption because we are dealing with addicts here. An addict can't chose to only smoke 5 on one day, they have to maintain their nicotine levels throughout their waking hours.
So the government is just maximising revenue. Smokers would not suddenly smoke more if the price of a pack was reduced to £3.00. Smokers would still in the main smoke 20 a day but the revenue for the taxman would be drastically reduced.
That folks is just sick, milking addicts for all their disposable income, while pretending to help them reduce their habit but actually doing no such thing. I can't imagine many things more unethical.