In 1974, 51% of men and 41% of women in the UK smoked cigarettes, accounting for nearly half of the population.
About 450 children start smoking every day, according to Ash
Now, just over one-quarter smoke. But the difference in that time in the percentage of young people who smoke has been far less marked.
As a survey for the BBC finds a majority of adults want the smoking age raised to 18, BBC News Online asks why the smoking message is not getting through to the younger generation.
In 2002, 38% of 20 to 24-year-olds in the UK smoked, making it the age group with the highest prevalence.
Yet, back in 1978 it was the older generations who had the highest percentage of smokers.
More worryingly for the anti-smoking lobby, there is very little difference in the percentage of 15-year-old secondary school pupils who smoke now compared to 20 years ago.
Amanda Sandford, research manager for campaign group Action on Smoking and Health, says there are a number of reasons why the younger generations are bucking the trend.
"Family circumstances and parental smoking and attitudes are significant," she told BBC News Online.
"Even if parents smoke, if they can say they strongly dislike it to their child, that can have quite a strong impact.
"Otherwise, if children see smoking as the norm they will want to copy it."
More than 80% of smokers take up the habit as teenagers while about 450 children start smoking every day, according to Ash.
One major reason for children and young people taking up smoking was because they saw it as something to make them seem grown up.
One-fifth of 15-year-olds smoke
One-quarter of 16 to 19-year-olds smoke
About 450 children start smoking every day
More than 80% of smokers take up the habit as teenagers
About 12m adults smoke cigarettes
About 70% of smokers would like to quit
Source: Office for National Statistics
"Most children want to be more adult and what adults do, they copy," said Ms Sandford.
"What we need to do is create a situation where smoking is not seen as the norm and where smoking is not acceptable behaviour."
That was why Ash campaigned for bans on smoking in public places, she added.
Peer pressure was also a factor together with "gratuitous" smoking in films and on television.
And she said the price of cigarettes was less likely to put off teenagers than adults because they were more likely to share them.
Ms Sandford conceded that there had been little reduction in smoking among the younger generations over the last 30 years.
She said: "As long as smoking is legal, and it would be counter-productive to make it illegal, then there will be kids who will smoke.
"We have to accept that."
But the most significant reason for the overall smoking picture now, compared to 20 or 30 years ago, was that almost as many young people were taking up the habit as in the past but that more established smokers were now quitting.
'Quit or die'
Smokers' rights group Forest says it does not want to see anyone under 16 smoking because "children smoking is often used as a stick to beat adult smokers with".
But it is critical of methods employed by the government and anti-smoking groups to tackle underage smoking.
Director Simon Clark told News Online: "The anti-smoking education that teenagers often receive is based on the 'quit or die message'.
"So many young people know smokers in their family, whether that be their father or their grandfather, and they know it's nonsense to say every smoker will die from smoking. They're no longer listening.
"They have to be given a much more balanced picture rather than being given what they perceive as propaganda."
Sixteen-year-olds should be given ID cards to solve the problem of underage sales rather than the local councils using "agent provocateurs" for "entrapment", he added.
Despite the relatively small reduction in the number of young people smoking over the years, Ms Sandford maintains the message is getting through.
"The latest figure for 11 to 15-year-old smokers is 9% overall," she said.
"If you turn that on its head then that's almost 90% that don't smoke and that's not a bad figure.
"Given that it's quite easy for kids to get hold of cigarettes, together with other factors and pressures, then we shouldn't be too hard on ourselves - the vast majority of kids will not take up smoking."