This collection contains correspondence, published articles, manuscripts, and experimental notebooks documenting scientist L. H. Gray's scientific work. Most of this work took place during his tenure as the first Director of the British Empire Cancer Campaign Research Unit in Radiobiology (1954-65), where he was free to choose his own research topics. Gray also corresponded with many notable scientists, including Sir James Chadwick (who discovered the neutron), and Ernest Rutherford (who discovered the proton). This collection also includes an extensive body of papers by D. E. Lea, another of Gray's colleagues.