Very doable as long as you don't linger. No passport control as it's int'l-int'l. Onward security is at the gate for the BHX flight. Your incoming flight from YYZ wil most liekly get to the E, D or F pier, and BHX from the D pier. If you walk fast, 10 minutes from one gate to the next max. As long as you're there before the flight closes, you're good as they can see you're coming through security.