Ark Royal was the closest aircraft carrier, and Force K was the response force. Those were practical reasons to send the formation to Montevideo. Even so, Ark Royal was Britain's premier strike carrier and the newest carrier in service, while Renown was a fast battlecruiser fresh from extensive reconstruction. Large sections of Renown were effectively new, which makes refit seem too mild a description of the work. The combined commitment appears excessive for blockade duty alone, particularly when compared with the Royal Navy's other actions later in 1939.
Notable Point · 0:45-1:40
The case for sending Ark Royal and Renown
Ark Royal was the closest carrier, and Force K was the response force, but committing Britain's newest carrier and a newly reconstructed battlecruiser still suggests an intention to fight.