This was my entry for the Map Contest, and I decided to make it a TL.
Spain refuses to fund Columbus's trip to find a new passage to India, and so, after being rejected by many other nations, he eventually sails for England.
When he returns, with news of a new Continent, it is decided that news of this should be kept from the rest of Europe, and the majority of Britain. To this end, after he gives them the information on Geography etc., Columbus and his crew are placed under house arrest. With no competition for control of the Americas, Britain dominates, and, after a few Decades, all of the Americas are under British control.
With the Americas under British Rule, Spain does not have any real wealth, and is invaded by France in 1650. With this, France grows in power, and, blissfully unaware of Britain's Empire to the West, declares war on Britain.
Britain, it's attention shifted from the Americas, sends an army of thousands into France, as they no longer need to subdugate the Americas