Mystery cutting? tool

This is a single handed tool - the handle being about 4/5 inches long. From the front protrude 2 thin blades, forming a V-head. Each of the blades has a cutting edge on both the horizontal and vertical planes. My thought was for cutting seams of something like that but it isn't a very heavy duty item. I believe it is of English manufacture but this one was picked up at a yard sale in Canada.