Electricity by Victoria Glendinning
Charlotte Mortimer, brought up in the narrow confines and high tensions of a London suburb, escapes from a world bound by strict conventions into one on the brink of change. She marries Peter Fisher, a fiery young prophet of the new science of electricity. But, in the country mansion which her new husband is wiring for electric light, she forms a liaison with the irresistible master of the house. Sensual, spirited, trapped once again, Charlotte struggles to find her way through the choices pressing upon her.