I have found reference to the 'Stores and Clothing Division'
of the War Office (which is what it actually says on the label). However, this is only around 1920-1, about 25 years too late for this style if it is a military item.
There are also a few features of the braiding that aren't quite right (even scaled down for an NCO pattern). In particular, the bottom of the skirt opening at the front on this kind of patrol jacket is pretty much always at least slightly rounded rather than squared. The braiding round the pockets is usually the other way round than shown here - as in this image: https://s-media-cache-ak0.pinimg.com/736x/53/6b/2b/536b2bae99f22559fef6519335878620.jpg
Taking these things together, I don't think this item is totally as it appears.