Buried in one of Thackeray’s mid-period novels – if not Vanity Fair, then Pendennis – is a passage which touches on the ‘man is an island’ theme of which so much early-Victorian literature consists. Here Thackeray addresses his specimen reader, envisaged as a well-heeled and rather complacent paterfamilias, snug before his fireside, and invites him to consider the mother and daughter sitting alongside him at the hearth. What are they thinking about? Their lord and master? Domestic cares and tribulations? No, Thackeray insists, madam is probably remembering an early admirer, cast off before her marriage; miss is recalling her last appearance in the ballroom. This idea of the secret life, the dense private palisade that surrounds the average human existence, impenetrable even by those closest to you, lies at the heart of Jane Gardam’s immensely accomplished new novel.