The UK is approved to spy on the US via Five Eyes.
It has access to all sorts of stuff in ways our government isn’t allowed, due to laws.
There is no US law against England spying on us, nor is there a law saying the US Government can’t provide access to systems.
That’s the con that they use. “Hey, I’m not allowed to spy on MY citizens, would you do it for me, and report what you find?” Works in all directions.