Great Britain is a Darwinist country. Their allies in the Great War include the other Darwinist countries of France and Russia. Deryn Sharp's story begins here in Leviathan. The Leviathan returns to Britain to pick up Dr. Barlow and her loris eggs. The Leviathan and its original crew are from this country. The fabrications used by Britain include tigeresques, elephantines, hydrogen breathing airships, and kraken.
As in the real world, Britain has a large empire and their power stretches around the world. Because fabrication was started in Britain by Charles Darwin, they seem to be the creators of the greatest fabricated creatures. Great Britain is ruled by King George V.