Health specialists, led by Nicholas Hopkinson, a senior lecturer in respiratory medicine at Imperial College London, have been lobbying MPs for the ban for several years.
Hopkinson says he is delighted by this week's decision. "This is an important step forward in protecting children from the harmful effects of tobacco smoke. The government must now move to implement this as quickly as possible," he says.
About 11,000 people die from passive smoking in the UK each year, according to Cancer Research UK. Anyone exposed to second-hand smoke at home or work has a significantly increased risk of heart disease and lung cancer.