Paul Parsons printed an in-depth feature in the April issue of Focus magazine on his book 'The Science of Doctor Who', which is not published by the BBC.
The title of the book is featured on the magazine's cover next to an image of the Tardis, with the strapline "The amazing real science behind sonic screw-drivers, cyberman, regeneration, and more".
Parsons mentions the title in his editor's letter, writing: "This month we've turned Focus's scientifically critical eye on the new series of 'Doctor Who', due to air imminently on BBC One... For the super keen, my book 'The Science of Doctor Who' is published on April 6, and you can get a free copy by subscribing to Focus".
A BBC spokeswoman said that with the new TV series of 'Doctor Who' to be broadcast next month, the April issue of Focus has 'The Science of Doctor Who' as a feature with an angle suitable to the magazine's popular science and technology content.
"Given that Paul is a Doctor Who expert, it was only natural that he write this article. 'The Science of Doctor Who' is offered as a gift to new subscribers in the April issue on the subscriptions page and in the editor's letter," she said.
Focus became part of BBC Magazines when BBC Worldwide bought Origin Publishing in 2004.
Origin bought Focus three years earlier from the National Magazine Company and the magazine's circulation rose 8% last year.
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