Thank you all for the replies. Having seen this in construction, I think the designer gave the main pieces to someone else to add the seam allowances etc.
The seams are to be pressed open and the 'extensions' on the end of the seam allowances then both face the wrong way.
The length of the piece that is given for the neck binding is about 20% shorter than I would expect to cut. Although the pattern is for a woven, it looks as if it could have drawn out by someone used to using jersey.
The final dress is very 'off the shoulder'. A tucked insert was added at the top of each sleeve so bra straps wouldn't show. (If it was my dress, I would add a picture here) We did a bit of fitting at the waist to take out a bit of slack making the back billow out, and tapered in the back seam at the neck by about 5cm. Makes pretty summer dress in a light cotton.