I like it.Okay, I'm gonna take a crack instead of just nay-saying.
Maybe the US sits out WWI, it ends with an Entente victory but at a terrible cost, perhaps an extra six months to a year of fighting. After the war ends France and Germany are basket cases, both their economies are wrecked by the fighting even more so than OTL. Europe struggles to recover deeply affecting the economies in North America as loans are defaulted on and the roaring twenties is stunted. Britain meanwhile is dealing with growing resentment at home, trade unionists and socialists are becoming increasingly agitated as a result of a costly war and economic malaise.
Eventually a violent Socialist revolution takes place in Britain, supplanting the ruling classes who flee the nation, Royal Family heads to Canada. Canada however has been more deeply affected by a worse Depression (exacerbated by defaults from France, Germany and now the UK) and the Communist party of Canada is more popular (at least with the workers) much to the chagrin of the conservative PM Bennett who reacts more violently towards the Communists (who had some popularity in OTL). Inevitably the Canadian Communists are outlawed and this causes civil strife, agitated by the revolutionaries in Britain. The US meanwhile is dealing with a far worse economic depression but manage to avoid any serious civil strife but rhetoric becomes even more anti-socialist as Britain (and seemingly Canada) turns Red. Global trade has been severely disrupted as Europe and Germany swing to the far right and squabble among themselves. Stalin laughs as the Capitalist West continues to collapse.
Despite everything, the US manages to pull itself out of the Depression (perhaps a more comprehensive New Deal in reaction to halt what appears to European Domino effect) and by the mid to late 30's makes the decision to "intervene" in Canada (perhaps at the invitation of the Royals/conservative elements) which becomes a wider conflict with Socialist Britain? The appropriately named War Plan Red is drawn up (updated for the situation, the US has not had the experience of WWI remember) and begrudgingly, the United States and The People's Republic of Britain (and to an extent Canada) march to war.
There's a few holes, but it's the best I got :/
Maybe the situation in 1919 was worse, but not to the extent of Valiant shelling Liverpool; a few dozens dead, more uncertainty about police and military loyalty after a few more mutinies. So the government plans for future trouble with the Civil Guard instituted and arms stockpiled for their use, with the socialists and unions also quietly preparing. So when the Great Depression analogue hits (let's call call it the Big Slump, I did in the EDC) the unions have their own 'Red Guard' (and maybe the 'Triple Alliance' of railwaymen, miners and TWF persists, they could have brought down the government in 1919) and a civil war of sorts happens.
You could then have it go either way; the purged police and army, assisted by the Civil Guard attempt to suppress the nascent revolution (which initially isn't actually a revolution). If they succeed then the UK goes "fascist" by another name (can't be using nasty foreign words). If they fail the socialists take over and anything from a social democrat republic to a communist state emerges. If the US goes in the other direction there's an ideological basis for conflict. Season perhaps with a delayed "Spanish" 'flu pandemic, conspiracy theories about biological warfare (where's Herbert George?) and more.
Maybe the US got meddlesome over Ireland in the 1918-20 period? Could a more united Irish American block have frustrated Wilson's attempt to bring the US into the Great War? Or provided overt support (the "Irish Legion" perhaps?). How about US military bases there? That'd be a suitable source of irritation.
ETA: Damn, I forgot to reference the KKK. That's the British KKK, the Kibbo Kift Kindred founded by John Hargrave[1] as a more pacifist (and more ritualised) mixed-sex version of the Scouts and Guides.
Later Hargrave founded the 'Green Shirts' (the Legion of the Unemployed or Legion of the Kibbo Kift) linked to the short-lived Social Credit party[2]. They were the largest uniformed paramilitary group in thirties Britain with all sorts of possibilities[3] should a revolution break out[4].
[1] Cartoonist, illustrator, wood carver, novelist, inventor, rock music fan and psychic healer. He also sued the British government for stealing one of his ideas and incorporating it into Concorde and forced a Public Enquiry. An interesting individual who simply begs for a bigger role in an AltHist, novel or RPG scenario.
[2] It's not a new idea.
[3] Seriously, a paramilitary street-army with links to strange woodland rituals? Founded by a man who claimed psychic powers? If you stuck them in in a CoC scenario people would complain about lack of plausibility.
[4] In my EDC timeline they have members with psionic powers, alien artefacts and links to time travellers and formed the nucleus of the resistance to the authoritarian British Republic until the Revolution came. Then things got really interesting.
Last edited: