Hi! I’m finding myself a bit lost for a paper in my history class in college and I can’t find a good source to answer my question for good.

What were Britain’s interests/objectives in the anglo-soviet agreement on the 12th of july 1941?

While it seems to me that Britain’s interest in the beginning of WW2 was also a lot focused around its empire, which was threatened by the Axis forces in Asia and the Middle-East (and Mediterranean?). However, with operation Barbarossa that started not long before july 1941, why would Britain sign an agreement with the USSR since the soviets were doing most of the fighting in the east and distracting the Germans? Was it to protect its colonies? I can’t find a reliable history source that answers my question!