Downton Abbey 2 trailer: Did Dowager have affair rendering Lord Grantham illegitimate?

DOWNTON ABBEY 2's latest trailer has left fans full of questions, especially surrounding if Maggie Smith's Lady Violet had an affair and if Hugh Bonneville's Robert Crawley is truly the legitimate 7th Earl of Grantham. As Lady Edith says in the new footage, "It doesn't look good for Papa", but also serious trouble for the rest of the family line including Lady Mary and George.