Showing In Pale Battalions by Robert Goddard

Six months after the sudden death of her husband, Leonora Galloway sets out on a trip to France with her daughter Penelope. At last the time has come when secrets can be shared and explanations begin... Leonora takes her daughter to the battlefields of WW1, where her father is commemorated on the Thiepval Monument. But the date of his death is surprising, and reveals that Captain John Hallows cannot possibly have been Leonora's real father.

This is only the start of a series of revelations that span three generations of a distinguished aristocratic family who are not what they seem. Penelope must piece together a tale of war, of loss, of greed, deception and vice - and the perpetrator of a murder left unsolved for more than half a century...