Penelope Lively 
According to Mark 

A respected literary biographer, Mark is working on the life of Gilbert Strong – a writer about whom he thinks he knows everything. Happily married, and apparently dedicated to a life of letters, he nevertheless falls in love with Strong »s granddaughter Carrie, a vague and unsophisticated young woman more interested in bedding plants than books or passion. As Mark »s obsessions develop over a hot, complicated summer, he begins to understand that nothing is ever what it seems; not Gilbert Strong, and certainly not himself.
According to Mark is a witty and moving look at love, literature and the dangers of middle-aged folly.