I actually redid the whole front end of the book to include some examples of iconic WW-I fighting knives and provide some background into the knives that Fairbairn and Sykes could have referenced before finalizing their design. I am of the opinion that Fairbairn had a rethink of how he wanted the new knife to be modified from the Shanghai F-S model. These changes were based on the difference between fighting Chinese gangsters in light weight clothing, to killing soldiers in heavy uniforms and battle gear. I believe his long voyage home from Shanghai gave him time to reflect on these changes. His basic design was solid, but it needed “beefed up.”
Fairbairn also knew one of the major obstacles he would face was finding a manufacturer who would make what he wanted, the way he wanted it, and who was not already operating at full capacity. We all know who ended up making the first ones. They made hundreds of thousands of them, but were they his first choice? I have the answer to that question in the book.