It looks like the smallest model of the classic Troutbag, also called the schoolbag. It came in three different sizes. First time I saw it in patent (?) They are not produced any longer. They were common in Scotchgrain black/branston or mole/brandy. Even earlier ones were marine, and there were other colours as well. They also came in congo black or brown leathers in different shades. Some three years ago there was a lighter version of this bag in scotchgrain black and mole. I have seen others in the same classic tartan as your but not patent. A very nice classic vintage model. Your looks brand new !