Duffel Coat recommendations sought

[Ticklishchap]

I am interested in choosing a Duffel Coat (or Duffle, if you prefer). While I haven't worn one since my teenaged years, when they gave way to Barbour jackets, I find that have a sudden wish for one now. I would like to get the most traditional one possible, of course, of a kind which I could wear on top of my favourite sweaters (Commando 'woolly pullies', Guernseys and a submariner's turtleneck. My strong preference is for authentic Naval (to reflect my interest in/admiration for the Senior Service).

Although I'm starting to look at UK stockists and investigate on-line, any advice and recommendations from you would be very welcome.