Hypothetical scenario, a little cliched too:
Edward VIII ascends to the throne in 1936 on the death of his father, King George V. He seriously contemplates marrying his partner, the divorced American Ms Wallis Simpson. However, his advisors and family prevail upon him to not foolishly abandon his obligations to his country, and he reluctantly accepts that he if he forces the issue he will be utterly humiliated. Consequently, he does not abdicate the throne and remains King of the United Kingdom.
Despite a reputation for being a personal admirer of Germany's Adolf Hitler, when the British Government's official policy becomes increasingly at odds with Hitler's ambitions Edward VIII sensibly withdraws and guards his opinion, not wishing to embarrass his Government. Nevertheless, unknown to the public he counsels Prime Minister Chamberlain to seek a peaceful solution to the "continental difficulties" and writes to various Ministers along the same lines. True to his word, he does not cause any political difficulties for the Government publicly.
Before long Hitler's ambitions cannot be sated by appeasement, and after the abrogation by Hitler of the Munich Agreement the British Government prepares for a showdown. Edward VIII continues to write to the PM and other Ministers about his misgivings of military preparations, and he criticises the Government's decision to guarantee Poland when there is nothing that can substantially be offered to Poland - a move, he argues, puts the realm at great risk, though he now states Hitler is clearly a menace to world peace and must be stopped. On 1 September 1939 Germany declares war on Poland, and Britain declares war on Germany 2 days later. Edward VIII publicly supports the Government and pledges he will do all he can to support the war effort. Privately he again raises his concerns about the lack of military preparations and criticises not the policy of opposing Hitler, but of the strategy. At this time he begins briefings with the Leader of the Opposition, Clement Attlee and uses the discussion to voice his private concerns in the strictest confidence.
After the rapid collapse of Poland, Denmark, Norway and the Low Countries, Prime Minister Chamberlain loses the leadership of the Conservative Party. Despite the King's personal support of Lord Halifax as leader, the leadership instead goes to the stalwart Imperialist Winston Churchill who rallies Parliament and the British nation to defy Germany. However, the rally is short-lived with the BEF being encircled by the German Army and Paris exposed to German occupation. A disastrous evacuation attempt effectively destroys the BEF. The loss is utterly humiliating and overwhelming.
The British public mood is traumatised by the rapid collapse of France and their armies, and Edward VIII in a discussion with PM Churchill is surprised to hear Churchill intends to continue fighting on. The Government nearly falls in a vote of no confidence, but after a fiery speech from the PM the Government manages to hold on by the skin of its teeth. However, before long the Luftwaffe begins bombing airfields and the city of London - British morale plummets further, and Churchill enacts emergency legislation to prevent open talk of "surrender" or "negotiation". Edward VIII, after receiving advice from constitutional lawyers, convenes a meeting in advance with Clement Attlee to discuss whether he would call an election immediately upon being named as PM. Attlee indicates that he would do so. Edward VIII then summons PM Churchill and asks that Churchill request him to call an election and seek a mandate from the people to continue the war. Churchill bitterly refuses and warns His Majesty that he (the King) proposes treason and capitulation.
Edward VIII promptly advises Churchill that he is dismissed as Prime Minister, and that Edward VIII will now appoint Clement Attlee. Upon being sworn in as PM Clement Attlee requests the King dissolve Parliament and call for new elections. The Conservative Party is in chaos and is overwhelmingly defeated at the election for being bitterly divided and, in the minds of many voters, being responsible for allowing Britain to be in such a weakened state. The newly elected PM Clement Attlee negotiates a ceasefire with Germany, opting to use the time to rearm and await a more opportune moment. That moment comes when Germany invades the Soviet Union in early 1941. In 1943 Britain, and the United States (at war with Japan), declare war on Germany and relieve the pressure off the Soviet Union.
The war in Europe ends in late 1944, and following the war fresh elections are held in the United Kingdom, returning the Labour Party to power with an enlarged majority. The role of Edward VIII and his early sympathy with Nazism continues to draw controversy until his death in the 1970s.