How would you get Britain to the point of revolution then?
Now that's a good question. I suggest a long, grinding and unsuccessful war, with serious incompetence in leadership to exacerbate things.
I'd suggest early ore pre-war PoDs with factors leading to a generally worse conduct of the war.
Perhaps the pre-war .280 rifle programme goes better and there is a shortage of weapons in the early stages, leading to worse British performance. We'd need the Germans to avoid an early victory but be slightly more effective and take a more defensive stance, allowing the British and French armies to inflict more casualties on themselves.
The Shell Crisis in 1914-15 has possibilities; perhaps the anti-government publicity is worse and their is a feeling that the Munitions of War Act is being used against workers and unions specifically, rather than against obstructive manufacturers?
Perhaps some German sabotage leads to workers being blamed.
Now, assuming the general shape of the war is similar, you'll have a mess on the Western Front. Sooner or later Wilson will find an excuse to involve the US (unless there are problems there; we've covered the possibilities of messing with McAdoo's actions in 1914 elsewhere on the forum). So in 1917 the Franco-British Nivelle Offensive goes badly wrong, with the Allies failing on a tactical level as well as strategically but the attacks are pressed (brutal et continu) well into the late summer.
By June the French have suffered 180,000 casualties, with 45,000 dead, and their medical services have collapsed. Britain has suffered 225,000 casualties and the whole offensive is perceived as a disaster.
French morale is at the point of collapse, British is badly shaken.
In June German counter-attacks have driven the Allies back beyond their starting points and French troops are rushed into a disastrous counter-counter-attack. While the Germans regroup French morale collapses and mutinies spread (on a larger scale than OTL) including into British units.
Faced with the prospect of further German offensives Pétain suppresses the mutinies by force, though some units refuse to fire on their comrades. He warns the government in Paris that a crisis has been reached.
Meanwhile British forces at Étaples and other camps have heard of the mutinies. Something sparks a crisis at one of the camps (let's assume the New Zealanders at Étaples). Scared MPs fire into a crowd, killing a dozen or so soldiers (and a couple of French civilians). The redcaps are overwhelmed by more than a thousand mostly unarmed troops and several are hanged from trees. The troops arm themselves and some work to fortify the camp, sending a list of demands to Haig. Others pursue the fleeing MP detachments into the town, where further violence by both sides ensues. The Commandant is locked in a cell, along with many of the camp officers and instructors.
Haig dispatches ordinary infantry, the HAC and a Machine Gun Corps detachment to suppress the mutiny. When the troops arrive some of the infantry refuse to fire on mutineers and clash with the officer cadets.
In late September tanks, machine guns and artillery is used to finally eliminate the mutiny. However sporadic acts of disobedience are occurring throughout the British Army and the French Army is collapsing. The Allies request a ceasefire and over the winter of 1917-18 an armistice is negotiated.
Bitterly disillusioned men return home, newly enfranchised by the Fourth Reform Act (earlier than OTL) and troubles are rumbling in Ireland.
