The average height of a solider in World War 1 was 5 feet 3 inches. In a study of 6000 soldiers from three inner London boroughs, only six people were above 6 feet tall, according to Dr Dan Todman of Queen Mary University, London. His research into the impact of the Great War involved trawling through the archives of solders' war records, enlistment documents and medical sheets. I was fortunate enough to attend a talk Todman gave at Brixton Public Library in September, where he also considered the average chest sizes of service personnel, which, along with their height, pointed towards malnourishment.
We also learnt that most of the death in service pensions were paid to parents, as the soldiers were too young to have found a bride. These were still the days when children cared for their parents, and thus pensions were geared towards them.
Those who signed up often lied about their profession, perhaps so that they might avoid the trenches. The skills that they would acquire, in say, engineering tanks, would help their job prospects at war's end.
In addition, desertion rates increased more rapidly after armistice, partly as a result of boredom. The British authorities left soldiers pretty much where they had fought for for a long time, owing to the fear of social instability that a rushed demobilisation would cause. Soldiers coming home to jobs that weren't there risked a rise in revolutionary fervour. To avoid the fate of other European countries, most notably Russia, the "dole" was introduced to ease transition.
More about Dan Todman and his work can be found here.