I think that the navy willis 9927 is a rather rare, I often see these bags in black, mahogany, and British tan with brass hardware but only rarely in other colors or with silver hardware. I have purchased and rehabbed both a gray/silver and a navy/brass willis in the past, but they are less commonly encountered.
In fact, I hesitated to buy my navy willis because it had a strong smell of cigarette smoke but it was the first navy one that I had seen IRL so I decided to risk it. I had an awful time getting rid of the smell and I put that bag through a lot, including giving it 2 baths and even tying it up in a lingerie bag and running it through the washing machine!
It came out looking great (and eventually I got rid of the smell!) you can see before and after pics at the link below. I wouldn't hesitate to dunk another navy willis in the sink with Dawn dish soap - it will improve the bag immensely. The water will turn bluish but don't panic, they really dyed those vintage bags deeply and you won't notice any color loss.
https://forum.purseblog.com/threads...l-out-of-2-leather-bags.796750/#post-23705362