Two years ago I picked up, on a whim, Sarah-Jane Stratford’s Radio Girls, and I fell in love. The book was the perfect blend of history, politics, and feminism. I’m pleased to say that with Red Letter Days, Stratford has done it again. While the protagonists share some superficial qualities—both move from North America to Britain, both work in communications industries in some capacity, both become somewhat embroiled in espionage and skullduggery—Stratford has…