Griffiths was born in Walton-on-Thames, Surrey, England, at the end of 1906, the youngest of three children of a middle-class family. Shortly after Griffiths' birth, his father was betrayed by a business partner and was left penniless. His mother took the children and established residence in a smaller home which she maintained, though she had to find work to support herself and the children. At age 12, Griffiths was sent to Christ's Hospital, a school for poor boys. The students of this school were nicknamed "bluecoats". He excelled in his studies and earned a scholarship to the University of Oxford where, in 1925, he began his studies in English literature and philosophy at Magdalen College. In his third year at university he came under the tutelage of C. S. Lewis, who became a lifelong friend. Griffiths graduated from Oxford in 1929 with a degree in journalism.