Who is Jennie Churchill from The Last Lion: Winston Spencer Churchill and what is their importance?

Jennie is Winston's mother. She is an American from a wealthy East coast family and meets Randolph at the age of nineteen aboard a shipboard party given by the Tsar of Russia. Jennie and Randolph are quickly engaged and Jennie is pregnant with Winston when they are married. She remains with her syphilitic husband until his death in 1895. Jennie is very active on the party scene and leaves most of Winston's upbringing to his nanny, whom Winston is very close to.