The Chaos TL by Max Sinister - Britain. The country underwent a revolution in the 19th century and became Socialist, later helped the Socialist Block come into existence.
Look to the West by Thande - The Kingdom of Great Britain, which never joined with Ireland in an Act of Union (LTTW started out as a Britain-centric TL, but rapidly diverged towards having a more generally European focus with global elements).
Know of any other timelines set here ? Feel free to add them !