Graham,
Dont just listen to one guy. Take your book to another for a second opinion and try again. And try some of the smaller publishers too. I am sure someone will show interest in the book even if its only a limited run. It gets it out there at least.
Oh I don’t worry about it! I’m a publisher in my own write ! (have been now for 22 years) but I like to spread the risk around some. If push comes to shove, I will end up producing it myself, but at the moment I have one or two other irons in the fire before I go down that road! I’ve turned up lots of piccies that have not seen the light of day for lots of years, so it a worthwhile project. I also do not think it was as much of white elephant tat a lot of so-called ‘aviation journalists’ have claimed in the past!