In their heyday between 78 and 83 the Angels were one of the dominant live and recording groups in Oz, at one stage overshadowing the likes of Midnight Oil and even AC/DC. Neeson's wild-eyed, exuberant, extroverted and at times unhinged stage persona was legendary. Every Angels concert was a rollercoaster of a show, with more energy than nuclear reactor. This energy was complemented by Neeson's offbeat and compelling lyrical output that showed a range of literary influences.
A decent article on him by ABC Australia can be found here. Note the 4001 he is playing in the video at the bottom of the article.
For a variety of reasons The Angels did not hit it big overseas, though a number of US acts cite them as an influence.
My first band based their set list on the breakthrough Angels album "Face to Face".
Here's some live clips from their heyday:
Vale Doc! You will be sorely missed!