A Different Argentina

"The South Sea Company was granted trading concessions in South America in the time of Queen Anne, under the Treaty of Utrecht. The British had long harboured ambitions in South America, considering the estuary of the Río de la Plata as the most favourable location for a British colony." [from Wikipedia]

"The Napoleonic Wars played a key role in the Rio de la Plata conflict and since the beginning of the conquest of theAmericas, England had been interested in the riches of the region. The Peace of Basel in 1795 ended the war between Spain and France. In 1796, by the Second Treaty of San Ildefonso, Spain joined France in its war with Britain, thus giving Britain cause for military action against Spanish colonies. Britain judged it the right moment after the defeat of the Franco-Spanish fleet at the Battle of Trafalgar. This battle forced Spain to reduce to a minimum its naval communications with its American colonies. Historically, Buenos Aires had been relatively neglected by Spain, which sent most of its ships to the more economically important city of Lima. The last time when a significant Spanish military force had arrived in Buenos Aires was in 1784.^{[2]"  [from Wikipedia]}

"There were six Anglo-Spanish Wars from 1702 to 1783, most of which lasted for several years and Britain had long harboured interests in taking control of the region from the Spanish before the invasions."[from Wikipedia]

"Back in 1711, John Pullen stated that the Río de la Plata was the best place in the world for making a British colony. His proposal included Santa Fe and Asunción, and would have generated an agricultural area with Buenos Aires as the main port. Admiral Vernon also declared the benefit of opening markets in those areas in 1741. By 1780 the British government approved a project of colonel William Fullarton to take the Americas with attacks from both the Atlantic (from Europe) and the Pacific (from India). This project was cancelled.^{[8]"[from Wikipedia]}

"Nicholas Vansittart made a new proposal in 1796: the plan was to take Buenos Aires, then move to Chile and attack from there the Spanish stronghold of El Callao in Peru. This proposal was canceled the following year, but was improved by Thomas Maitland in 1800 as the Maitland Plan. The new plan was to seize control of Buenos Aires with 4,000 soldiers and 1,500 cavalry, move to Mendoza, and prepare a military expedition to cross the Andes and conquer Chile. From there, the British would move from sea to seize Peru and then Quito.^{[9]"[from Wikipedia]}

"All these proposals were discussed in 1804 by William Pitt, Lord Henry Melville and Sir Home Riggs Popham. Popham did not believe a complete military occupation of South America was practical but argued for taking control of key locations to allow the main objective, to open new markets for the British economy. Although there was consensus for weakening Spanish control over its South American colonies, there was no agreement as to the system and the moment to take such action. For instance, it was not even agreed whether the cities be turned into British colonies after their capture or just be made into British protectorates.<sup>[11]"[from Wikipedia]

Now if the British were somehow successful in taking over the Spanish viceroy of Rio de la Plata during the Napoleonic Wars, the history of South America and if possible Latin America would greatly change due to major British influence in its new colony of Rio de la Plata. Eventually immigrants and migrants all the way from England, Wales, Ireland and Scotland would eventually settle in Rio de la Plata, thus intermarrying with the Spanish locals. Rio de la Plata would be just like Canada, having two spoken languages, many unique cultures and traditions. It would be literally the "Canada of South America". 
Eventually Rio de la Plata would too just like Canada, Australia, New Zealand and South Africa, would be come a dominion in the British Empire. 

And of course by the Rio de la Plata Act of 1979 would finally allow Rio de la Plata full independence from Britain. It would be a member in the Commonwealth as a major member. It would have great relations with its neighbors of Brazil, and Peru. And with Australia and New Zealand being in the Pacific Ocean, i would provide Rio de la Plata more trade along with trading with South Africa and India. 

If British were successful in taking over the Spanish viceroy of Rio de la Plata, history of South America, and Latin America would change greatly! It would create a "Canada of South America".</sup>