Showing cigarette brands on fictional TV shows is "unnecessary" and of "questionable legality", experts have said after they found that tobacco branding is "particularly common" in popular soap Coronation Street.
Researchers said there should be tighter regulations on television programmes with "gratuitous depictions of tobacco" after they found that one in eight programmes show people smoking and 34% contain some form of content relating to tobacco.
The authors, from the University of Nottingham and King's College London, said smoking in films is a common cause of children's smoking experimentation and uptake.
They measured the extent to which tobacco content occurs in prime time TV by examining BBC1, BBC2, ITV1, Channel 4 and Channel 5 between 6pm and 10pm for three separate weeks in 2010.
The study, published in Tobacco Control, found that 73 of the 613 programmes aired showed actual tobacco use and 210 contained tobacco content including people smoking, implied use of smoking, tobacco paraphernalia and tobacco brands.
The authors said the presence of "clear and unambiguous" tobacco branding was rare, occurring in just 18 shows, but they said tobacco branding is "particularly common" in Coronation Street - with brands appearing in six episodes. They wrote: "The programme with the most brand occurrences was an ITV1 soap opera, Coronation Street."
Tobacco advertising, promotion or sponsorship are banned in the UK but TV shows can still show smoking imagery for artistic or editorial purposes.
The authors wrote: "Tobacco content remains present in a third of all primetime free-to-air television programmes broadcast in the UK. Although much of this imagery comprised paraphernalia including no smoking signs, actual tobacco use occurred in 12% of programmes, predominantly feature films, reality television and comedy genres."
Two of the soap's sets are a newsagents and a corner shop so, as in reality, tobacco products are shown in the background. In 2015, when it becomes illegal for smaller shops around the country to display such products, the show will reflect the law and stop showing them.
A Coronation Street spokeswoman: "Soaps by their nature are reflections of real life and therefore show characters who smoke and shops where tobacco products are on sale. However, we do strive to balance dramatic realism with social responsibility; and ITV soaps work to specific guidelines and are careful not to condone or to glamorise smoking in any way."