Yeah, I saw Redgum live many times. Their path went along the lines of acoustic part-time band to acoustic full time, to folk-rock full time, to "founder members leaving but carrying on with no great success any more". All the time being a very political group. Trevor Lucas produced and appeared on a couple of their albums, plus the 1983 national #1 single "I Was Only 19" which had Trev on backing vocals on the chorus. This was a song about the plight of Vietnam veterans so its success was surprising but welcome. "Frankie kicked a mine the day that mankind kicked the moon / God help me, he was going home in June..." TL did a version of this with Fairport at Cropredy '85.
The main focal point was singer/songwriter John Schumann who very nearly became a member of parliament in the late 1990s. He also hosted a children's TV show for a while. His Australian accent is a rather broad one.
Re Caught In The Act - it's pretty good but is the acoustic version of the band, pre-hit single though it has an earlier version of 19 on it. It's good to have and is one of the few Redgum CDs available now. There is also a compilation called Against The Grain:
http://store.countrymusic.com.au/store/products/item1818.inetstorewhich has a broader overview. More details about Redgum at
http://www.geocities.com/redgum_music/MH