[5] Kirwan's mother was a singer[6] and he grew up listening to the music of jazz musicians such as Eddie Lang, Joe Venuti, Belgian gypsy guitarist Django Reinhardt and 1930s–40s groups such as the Ink Spots.

[8] Boilerhouse played support slots for Fleetwood Mac at London venues such as the Nag's Head in Battersea[9] and John Gee's Marquee Club in Wardour Street.

[10] Mick Fleetwood recalled, "We met Danny at a little club in Brixton, the Nag's Head, one night when we played with a local band called Boilerhouse.

[23] Three days after that the band began a 50-date tour of the UK and Scandinavia, and at the end of November they were in Paris,[9] performing in a New Year's Eve show for French television [ORTF 'Surprise Partie'] with The Who, Small Faces, Pink Floyd and The Troggs.

[9] He and Marshall Chess arranged a two-day recording session[9] in which Kirwan, along with Green, Spencer, McVie and Fleetwood, played with legendary blues musicians David 'Honeyboy' Edwards, Walter 'Shakey' Horton, J.T.

Green had told Kirwan when he joined the band that he would be responsible for half of the next album,[9] and the songwriting and lead vocals on Then Play On were split almost equally between them, with many of the performances featuring their dual-lead Gibson Les Paul guitars.

Kirwan's varied musical influences were evident throughout, from the flowing instrumental "My Dream" to the 1930s-style "When You Say", which Green had earmarked to be a single until his own composition "Oh Well" took shape and was chosen instead.

[14] Mike Vernon noted that Kirwan's presence and his eclectic musical influences "were already beginning to take the band out of mainstream 12-bar blues and into blues-rock and rock ballads.

[9] The US track-listing of Then Play On was reordered to allow the inclusion of the full nine-minute version of Green's hit single "Oh Well", and two of Kirwan's songs, "My Dream" and "When You Say", were dropped.

[14] The track listing on The Vaudeville Years contained five Kirwan songs: "Like It This Way", "Although the Sun Is Shining", "Love It Seems", "Tell Me from the Start", and "Farewell", plus a joint composition with Green, "World in Harmony".

Mike Vernon recalled "considerable input" from Kirwan in the making of "Man of the World",[30] which was released in April 1969 and reached number two in the UK charts.

Producer Martin Birch recalled Green growing increasingly frustrated because he could not get the sound he wanted, and Kirwan reassuring him that they would stay there all night until they got it right.

[9] In January 1969, Kirwan made his first musical appearance outside Fleetwood Mac when he contributed to Otis Spann's blues album The Biggest Thing Since Colossus with Green and John McVie.

[37] Kirwan's songs on Kiln House included "Station Man", co-written with Spencer and John McVie, which became a live staple into the post-1974 Buckingham-Nicks era.

[46][47] Until then Green had kept a relatively low profile, but in his last ever performance with Fleetwood Mac, he and Kirwan and the band "took the place by storm" with a four-hour improvised version of "Black Magic Woman".

[58] Kirwan began an 11-month tour of America and Europe with the band, opening a couple of dozen shows for Deep Purple and for several months playing second on the bill to Savoy Brown.

As the tour progressed he became withdrawn and isolated from the rest of the band, got into arguments with Welch and was drinking heavily[9] to the point where, Fleetwood said, "alcoholism began to take hold.

"Danny's Chant" featured heavy use of the wah-wah guitar effect and was essentially an instrumental piece, except for Kirwan's wordless, rhythmic scat vocals.

"Bare Trees" and "Child of Mine", which touched upon the absence of Kirwan's father during his childhood, opened each side of the LP, and under Welch's influence[51] showed funk and slight jazz leanings.

He likened "the kind of music the new Mac plays" to "the moody rock of the middle-period Beatles" and commented on the resemblance of Kirwan's style, with his "deft melodic touch", to Paul McCartney's.

Scoppa ended the review by saying: By the summer of 1972 Kirwan had been writing, recording, touring, and performing continuously for nearly four years, since the age of 18, as a member of a major international band.

[12] Backstage before a concert on the 1972 US tour to promote Bare Trees, he argued with Welch over tuning their guitars and suddenly flew into a violent rage, banging his head and fists against the wall.

"I would say, 'the guy doesn't show up to rehearsals, he's embarrassing, he's paranoid, we've spent five hours dealing with him', but Mick, John, and Christine remained loyal to him because he was Peter's protégé.

"[70] Walker said the band had not functioned properly because "perhaps we were not focused enough musically, and in addition, Danny Kirwan's problems were just starting, and this made communication extremely difficult.

[72] In 1974, Kirwan worked again with Mick Fleetwood at Southern Music Studio in Denmark Street, London,[41] in recording sessions for the second album of London-based blues band Tramp.

One song, "Look Around You", was written by fellow Mac refugee Dave Walker, with whom Kirwan had worked in Hungry Fighter a couple of years previously.

[70] Kirwan's last album, Hello There Big Boy!, recorded in London in January 1979, featured guitar contributions from his Fleetwood Mac replacement Bob Weston on two tracks, "Getting the Feeling" and "You".

"[83] In the late 1970s Kirwan's mental health deteriorated, and after a difficult time recording his final solo album in January 1979,[84] he played no further part in the music industry.

"[87] In 1993, Fleetwood contacted the Missing Persons Bureau in London from Los Angeles and Kirwan, then aged 42, was traced to the hostel for the homeless[86] where he had been for the past four years, "carrying all his worldly goods in a rucksack" and living on social security and small amounts of royalties.

[77] Music writer Martin Celmins met Kirwan at a hostel in London where he was staying and managed a brief interview, which was published in The Guitar Magazine [UK] in July 1997.