Funny enough, I collected a mate from Brighton hospital yesterday, and there's loads of cyclists acting like complete twats in the city, I've never witnessed such behaviour, maybe the sun got to them.
I always leave plenty of space when I overtake them, yet they are happy to speed past on the inside with just inches to spare, or cut across in front of me to turn right, with no warning whatsoever, and forcing me to brake hard, suddenly weaving out of the cycling lane into the car lane, to over take, without even looking, etc. etc.
Having to put up with that behaviour all day long, on a daily basis, it's hardly surprising that some professional drivers get aggressive with some of the cycling twats.