I think he means “other defeated WWII nation and is also an island.”
I get that, but it still doesn't really apply. England wasn't firebombed and nuked into the stone age the way Japan was, and it still controls overseas territory. And let us not mince words, there was most definitely an element of racism in the pre-and post-war treatment of Japanese militarism, attitudes that would not be present in regards to the UK. As far as the British would be concerned (based on what was revealed in the books) they did nothing wrong except look the other way as regards the Freedomite atrocities. the Atom Bombing of Hamburg can't be called a war crime unless the US and Germany also want to confess to the same, and even as regards the start of the war, the French declared war first and the British simply followed them in.
I could foresee them being forced to surrender whatever portions of the Empire they still hold, reduce the Royal Navy to a regional defense fleet with nothing heavier than a cruiser and no carriers, and officially forswearing any claims to Irish, Canadian and Australia/New Zealand territory, and maybe the Royal Family being reduced to a ceremonial status ala Hirohito, but that's about it.