Further to this I have copied the code in this post (2-legged OAuth): http://code.google.com/p/google-gdata/source/browse/trunk/clients/cs/samples/OAuth/Program.cs, substituted in my API id and secret and my own log-ins, and it works.
So it appears my domain setup is fine (at least for the contacts/calendar apis). However swapping the code out for a new Spreadsheet service / query instead, it reverts to type: remote server returned an internal server error (500). How the heck am I supposed to work this one out?
