Or can you only work for the Hell Embassy in London
You can do actions that benefit the Convention, but you can’t be allied to them or really do anything that is favoring it in-character, major spoiler for details
If you give information to the Embassy without double-checking, your character is furthering the goals of the Convention, why this is the case becomes obvious if you do doublecheck.
I don’t think the double check always provide the same results.