When their leader, Peter Green, left, Fleetwood Mac regrouped with Kirwan and Jeremy Spencer as songwriters and lead vocalists. This incarnation of Fleetwood Mac made one album, 1970’s excellent Kiln House. It’s very different from their prior blues-based albums or their later hits with Lindsay Buckingham and Stevie Nicks.
I have attached links to three songs from the album. “Earl Gray” is an instrumental written by Kirwan who also is the lead singer on his composition “Tell Me All the Things You Do”. Kirwan is lead singer and co-author of “Station Man”
I saw Fleetwood Mac in late 1971 with a very different lineup. Spencer was gone and Christine McVie and Bob Welch had joined the band. They sounded nothing like the Kiln House band and didn’t play much from that album.