With the help of the Corsetmakers LJ community I found some more information about 1910s corsets.
Seems women wore a bra with the under bust corsets (and that overbusts were available but rarer) I was directed towards google patents search and found this one, designed by Marie Perrillat, that is on the right period for the corset pattern I'm using and looks moderately easy to reproduce.
I think my next task is to try and find some 1910s pin up girls so i can see the underwear 'in the flesh' corsets on mannequins and stylised fashion illustrations can only go so far. There must be some some 'What the Butler saw' films out there.
I've also found some more sources, this time extant 1910s clothing in museum databases. Kendra of Démodé has a list of links to these here .
She also has dress diaries of a couple of teens dresses and a collection of fashion plates from 1913 and 1917.
Also have a look at the headers and some of the buttons, lovely deco style line art of 1910s fashion.
The boyfriend has hopefully borrowed Norah Waugh's Corsets and Crinolines from the library for me, but the uni library doesn't seem to have Nancy Bradfield's Costume in Detail, 1730-1930 or Janet Arnold's Patterns of Fashion.