Permissions with NFS and native windows file sharing of same folder

I have a folder shared via NFS, and also via native windows file sharing. I'm using username/uid mapped via AD and I thought it was working all OK.

I've now found that all files created via a windows share end up being owned by the creating windows user and domain users AD group, with unix style mod bits of 700. I'd like the mod bits to be 777, or at least 755. The containing folder is set to 777 - why aren't new files/folders inheriting this?

Basically I want all files to be available to all users via SMB and NFS. I will be enforcing some security via permissions on the share.