Kirwan's legacy was in helping keep the band alive after co-founder Peter Green left. The band was primarily a great rhythm section at that point, with Fleetwood & McVie. But they needed a songwriter to tie it together. Ultimately McVie's wife Christine would take that role. But Kirwan came in on the transitional album Then Play On. He then wrote songs and did lead vocals on Kiln House. Kirwan wrote and sang lead on Tell Me All The Things You Do. Those two albums helped get them to Bare Trees and Future Games, where Bob Welch took over Kirwan's role as creative force. His hit "Sentimental Lady" transitioned the band from a guitar-based blues band to the soft rock powerhouse it became once Lindsay Buckingham & Stevie Nicks were added. Both Bob Welch and a later guitarist, Bob Weston, died in 2012.
