Did Britain control Persia in 1900?

No, Britain did not control Persia (modern-day Iran) in 1900, but it had significant influence over the country. The British government, along with Russia, had established spheres of influence in Persia, primarily to secure trade routes and protect their interests in the region. The Anglo-Persian Agreement of 1919 would later attempt to formalize British control, but in 1900, Persia remained an independent state, albeit with considerable foreign intervention in its affairs.