MYFLYLONDON.com has cut a video for you that shows How FLY LONDON Shoes Are Made - The Making Of FLY LONDON Shoes.
The soundtrack is the original Portuguese language (you can mute the video), none of us in the family know Portuguese well enough to create English subtitles, sorry - maybe you?
Pure curiosity aside, this video may help you appreciate the reason for size variations of FLY LONDON shoes. As you can see here documented on MY FLY LONDON: FLY LONDON shoes are still handmade to a large extent.
This of course results in greater size variations, which is no problem at all if you buy your FLY LONDON shoes through MY FLY LONDON from Amazon: You can send shoes back for free for an exchange for other shoes or money back, as long as you haven't worn the shoes outside: The sole must be unscathed too.
The final stage in the FLY LONDON shoe manufacturing is the delivery - with these cute FLY LONDON trucks.