This is from the www.georgelowden.com website. It's what he has to say about the "S" body shape :

   
Nick Webb of Acoustic Alchemy approached me in the early 90's and asked me to design a small guitar. This is the result. It is not quite a parlour guitar, it is about the same size as a classic guitar. I designed the soundbox profiles to accentuate the bass in an attempt to keep the bass loose and free and hopefully reasonably deep! When I finished the proto type in my own workshop, I immediately took it to the house and sat down to play it. I didn't want to let it go!