Stuck at red lights in 3 lanes of traffic. I was in right hand lane to turn right, at the front of white line and railings to my right so couldn't pull to the side. Middle lane for straight on. Left hand lane (towards hospital) is always allowed to filter through first via green light to the left, then after a while, the forward and right turn green lights come on. Ambulance comes up my lane whilst red traffic lights on. Blue lights and sirens on, all while the ambulance is indicating left (I am the only car in this lane, other lanes have several cars in). Ambulance leaves sirens on, and even beeps while lights are on red ( though i am not 100% sure this was the ambulance, but don't know who else it would have been?). From what I have read, you should not cross during a red light even for an emergency vehicle, I would have been entering a box junction? Was I BU to not cross the red light? And I think the Ambulance would have been quicker going in the left lane which filtered through first? Very confused. TIA