The Tartan found inside of the real trenchcoats is known as the Burberry Check Corporate Tartan No. 1239. It is restricted to Burberry Ltd. but in the last 10 or so years it has become very fashionable and can now be seen on just about everything.
In London, New York and LA if a woman did not have at least one item of Burberry Tartan she would be looked on as woefully outdated or worse yet poor.