Warden studied at Dr Challoner's Grammar School and received a B.A. Honours in History at Churchill College, Cambridge, 1994. He married actress Lucy Barker on May 1 2004.
He is probably best known for his appearances in Band of Brothers, as "1st Lt. Harry Welsh", in the BBC docudrama "Dunkirk" as Major Phillip Newman RAMC and in the HBO/BBC2 original historical drama, Rome, as "Quintus Valerius Pompey". He also appeared in "Evol" (2006) with wife Lucy Barker, and in the film version of Bravo Two Zero.