The title is telling, because all the characters here have lies to tell. Not all those lies are the dreadful kind that might hurt, but lies to make others happy; and of course there is always lieing by omission. Her descriptions of early 20th century farm life, and, of course, life (and death) in the trenches during that dreadful time (which certainly was never "over by Christmas") are drawn so clearly that you can see and feel it all. When she writes to describe meals she is cooking for Tom, her husband, Kezia lies. When Tom writes to her from the trenches, he is careful to leave out descriptions of the bloody torment that he sees daily in the trenches. When his sister Thea, who is Kezia's best friend joins the fray as an ambulance driver, she cannot tell either of them why. So the care and management of lies are both well practiced here.
There are plenty of books written around and about WW1, but if you have not read this one I recommend it.