We all know that TV programmes can help to set trends. Mad Men, Sex and The City and Desperate Housewives have all helped to set trends and have made fashion stars out of Sarah Jessica Parker, Christina Hendricks and Marcia Cross. But the latest TV trendsetter may just raise a few highbrows, as well as lowering a few hemlines. For the latest show setting the fashion world alike is Downton Abbey. Yes, you heard correctly, the period drama Downton Abbey, currently stuck somewhere in World War One. Debenhams are just one of the stores who are feeling the Downton effect, with fashion fans eager to copy the style of Michelle…