A Spy in Winter

The principle character us still missing. In the lives of Burgess, Maclean, and Philby we discern his hand, his influence, his shadow. Never once do we see his face or consciously hear his name. He is the Soviet recruiter. For these men were recruited. By whom?
Betwen the ag;es of neneteen and twenty-one, it seems, these children of Cambridge were recognized, courted, and consciously seduced into a lifetime of deceit. By whom?