Bluetit combat

Had a good day checking things and surveying all round the nature reserve. I got lots of photos and was beginning to think which one I would blip as I got back to my car. Then, while I was taking my wellies off at the back of the car, I heard a loud tapping sound, but couldn't locate it. Eventually, I looked along the side of the car that was close to a hedge and found a bluetit extremely agitated about another bluetit it had discovered in my wing mirror. It was attacking the other bird (image) relentlessly, presumably to protect its territory. A second bluetit (its mate?) was flitting about close by, watching the great battle. I observed this mortal combat for over 5 minutes, then began to feel sorry for this little battling bluetit and rather concerned for its beak which was hammering away on the glass of the mirror. I started to drive the car so it was well away from the hedge, but for a short while the feisty bluetit stayed with me. I hope it is now recovering, having seen off a fearsome rival AND an enormous blue car today.