Sherlock star escorts Patty Hearst's daughter on the red carpet
Benedict, 35 – who previously dated fashion designer Anna Jones – even took his new American love to Elton John‘s Oscars bash.
Lydia is a fashion model as well as an actress and columnist.
The stunning green-eyed socialite is also heiress to great-grandfather William Randolph Hearst’s publishing fortune.
Read more celebrity Love Juice in the latest issue of Now magazine dated 12 March 2012 – out now!