Help identifying possible WW2 naval coat

[zeroten]

I've recently acquired this coat and despite much effort I've not been able to find out anything about it. It looks almost like a duffle coat but without a hood and with a three button closure. I originally thought it could have been a naval explorers coat, however there is a label inside which looks like it would be a dated broad arrow one. From reading other posts, there seems to be lots of knowledgeable people out there, so any help would be greatly appreciated.