More than 80 years after the slaughter of the trenches ended, the remains of the fallen are still being unearthed, and Army investigators are using modern forensic techniques to try to find out who they were.
Ms Sinfield is a forensic anthropologist - an archaeologist specialising in the analysis of skeletons - and last month she was examining the remains of eight British soldiers found in the Somme.
"You do find yourself looking at an individual, and you can get a good impression of height and age," she said. "Especially with the younger ones you find yourself thinking, `You poor soul. What were you doing there?' "
The experience has stirred her interest in the old conflict, and given her a greater awareness of the significance of remembrance, although it is a memory she has always observed. Armistice Day on Thursday, she said, was "quite strange".
The farmers of Belgium and France ploughing the fields where millions fought and died regularly turn up a "harvest of bones" from these battles. Of the 1.1 million Commonwealth soldiers, sailors and airmen killed in the First World War, 527,978 have no known grave. The Thiepval memorial in France commemorates 72,000 such names from the Battle of the Somme, in 1916.
The relics of about 20 bodies are found every year, but in September a single site near Ypres in Belgium being developed as an industrial estate yielded 24 sets of remains.
If there is no chance of identification, the bodies are immediately reburied in the nearest military cemetery, under a headstone saying simply "Known Unto God". But those still with regimental badges, buttons or other kit are stored in boxes for further investigation at one of two mortuaries run by the Commonwealth War Graves Commission.
These inquiries are the responsibility of an Army department called the casualty and compassionate cell, whose normal work involves caring for the families or soldiers killed or injured in present-day operations. If a First World War body can be identified, the family is invited to attend the reburial.
Ms Sinfield, 30, who is based in Edinburgh, contacted the department last year, offering to help. Some of her other recent grisly tasks have been identifying bodies in mass graves in Bosnia and Kosovo.
"I suppose it is a bit of a peculiar thing to do, and it can be tough," she said. "But I feel it is something worth doing. It gives you a chance to actually help people, which you don't get with normal archaeology. Knowing what happened to their loved ones is obviously very important for families."
Extensive knowledge of how bones develop means she can quickly establish an age range, and heights can be accurately estimated from just a single thigh bone. Whether someone is left-handed can also be established by the thickness of an arm bone, and dental abnormalities, often also found in descendants, also add to the picture. All these details are put together with any clues found with a body.
Details of battlefield skeletons are cross-referenced with Army records to try to establish the identity. A spokeswoman for the casualty and compassionate cell said they hope to identify two of the eight bodies examined by Ms Sinfield. She often cannot accurately determine a cause of death, but she found two of the skeletons had cut marks consistent with bayonet wounds.
Artefacts found with the soldiers can bring the most emotional responses. In one box a short length of barbed wire was lodged in the man's helmet, and Ms Sinfield found this particularly poignant.
"It immediately set me thinking of all those photographs from the war, with mile upon mile of barbed wire," she said.
Ms Sinfield also brought back a small tin containing a greasy substance, which she is having analysed. She feels it may well be moustache wax, and the soldier could have had a magnificent set of whiskers.
"The contents still have fingermarks in the surface where whoever it was scooped some out for the last time before he was killed," she said.
"Something like that does give you a slightly odd feeling, a direct connection with the past in quite a personal way."