Private Ord. S. number 105 was sent home, wounded on 8.8.1917. He doesn't appear in the list of soldiers in the Battalion in November 1918 at the end of the war, so presumably he wasn't sent back to the front or he may have been transferred to another unit.
The 19th Battalion were at the Somme, they got to the woods west of Mailly-Maillet on the 6th July 1916. There job was to go into no-man's land, and construct a new jumping off trench 1000 yards long, 100 yards in front of the existing line. They had three nights to do the work. They lived in the woods and down in the hollow were 8 inch and 15 inch guns which shook the earth. Even though it was summer the duckboards in the trenches were covered over with 2 feet of yellow water. It took troops two and a half hours to reach the front line from the woods along a communications trench and this trench was often shelled by the enemy. When they got to the front the sight was appalling. " the dead lay in three regular parallel lines. three waves of Inniskillings and Newfoundlanders lay there as if on manoeuvres." While they were building the trench one wounded Inniskilling dragged himself into their trench. He had been in no-man's land for 6 days, inching himself back every night. By dawn the 19th Pioneers had to be clear of the trench. They came back to the woods covered in yellow mud from head to foot to sarcastic remarks from their mates. Three of the Pioneers were killed building that trench. They were at the Somme through July and August and the account I have read in the regimental history is terrible. "Tragedy, infinite tragedy lay in all directions". The !9th Battalion was a Pioneer Battalion, which meant "they were there, not to fight, but to work and be shot at."
Your Granddad was more than likely wounded at Villiers Fauchon on 12 July 1917. "W' Company was working in a system of trenches called the Bird Cage. It was continuously straffed by the enemy, especially with trench mortars. The enemy were seen off by return fire, but they were bombarded again until 1.15am. There were six killed, 23 wounded, 11 wounded 'at duty' and 6 died later in hospital. The company were congratulated on their work by the Divisional Commander the next day. That was the last casualties they saw before your Granddad was returned home, so he may have been in hospital in the intervening time.
All the information given is from my grandfather's copy of the Historical records of the 19th Battalion, Northumberland Fusiliers.