The 7th Infantry was part of the 2nd Infantry Brigade of the 1st Division, 1st Canadian Corps. So their patch was a Red square with the top half of a Red circle on top. You would have to check which Militia unit their were fed their recruits from to determine their ‘colours‘ or even if they had some. Many units in the 1WW were fed by several draws from across the country and their battle honours were distributed to the units whose troops made up the most of the unit at the time of the battle (In theory anyways). Some units only had ‘Kings‘ Colours which would have been a variation of the Red Ensign, so it still comes back to Red. You may want to try your luck for more info on some of the Militaria sites, Canadian history is fairly popular. Hope that helps. js