During his apprenticeship as the singer in Dublin bands the Black Eagles, Skid Row and Orphanage, Philip Lynott almost exclusively sang other people’s material. When he made his first forays into composition, the results were more Astral Weeks than Waiting for An Alibi: on early songs such as Dublin, Saga of the Ageing Orphan, Remembering and Shades of a Blue Orphanage, he reimagined his home city with the same impressionistic nostalgia Van Morrison used to conjure up postwar Belfast. Thin Lizzy were formed in 1970 by Lynott, former Them guitarist Eric Bell and ex-Black Eagle drummer Brian Downey, and released their patchy debut in April 1971. Originally written as a poem, Dublin was released a few months later on the New Day EP. Long before Lynott thought to use mythic Celtic imagery as a monolithic form of band branding, the song suggests a more conflicted relationship with Ireland. Themes of lost love, entrapment and exile are set to a gorgeously faltering melody and the gentle susurrations of acoustic guitar punctuated by eloquent electric counterpoints. Rooted in Lynott’s fascination with the folk and poetry scenes of 60s Dublin, this beautiful, disarming ballad suggests he could easily have followed an entirely different career trajectory.

This floor-shaking 1973 single lays persuasive claim to being the first bona fide Thin Lizzy classic. The band were fresh from an eye-opening tour with Slade, and from its explosive guitar riff – a proto AC/DC thug of a thing – to its roll call of tough-guy mannerisms, The Rocker is the sound of a band shrugging off the hippyish robes of their first two albums and slipping into something considerably sharper. Bell’s extended guitar solo is monumental, and although the lyrical imagery is route one – sex, violence, music, motorbikes – it’s highly effective. On The Rocker, Lynott inhabits a new, street-smart persona, hanging with “the boys” in the juke joint, watching the “chicks” and “looking for trouble”. While it’s possible to divine tongue-in-cheek humour in this heightened self-portrait, it presented a vision of the quintessential rock star that he would find himself increasingly striving to live up to, not necessarily to his long-term benefit. Seek out the full-length version on the excellent Vagabonds of the Western World album for maximum kicks.

Lynott’s family history was complicated. His mother, Philomena, ran away from Dublin to England and in 1949, aged 18, gave birth to her son out of wedlock. Growing up, Lynott never knew his father, a Guyanese immigrant called Cecil Parris who revelled in the nickname “The Duke”. After a few years living a tough and transitory life with his mother in the north of England, Lynott was sent to live with his grandmother in Crumlin, an estate in Southside, Dublin. Almost 20 years later, history made a decent stab at repeating itself: in 1968, Lynott fathered a son who was given up for adoption without the singer ever setting eyes on him. These complex familial currents flood into Little Girl in Bloom, written and recorded in 1973. Concerning a young woman and the secret “she carries in her womb”, Lynott sings as both abandoned child and absent father, while the trio deliver a performance of subtle and understated power. The opening thrum of feedback leads to an off-beam, almost post-punk bass figure, overlapping lead vocals and the soon-to-be familiar twining of two electric guitars. Musically, it points towards the layered sophistication of Thin Lizzy’s second incarnation. Lyrically, it sheds light on the most deep-rooted of Lynott’s demons.

Beloved though it undoubtedly is, Thin Lizzy never had much time for Whiskey in the Jar, their breakthrough hit, which inched into the Top 10 in February 1973. A venerable Irish folk song torn apart and then thrown back together for kicks during rehearsals, the band always regarded the single as something of an embarrassing novelty, so much so that the classic Thin Lizzy line-up – formed in 1974, with Californian Scott Gorham and Glaswegian Brian Robertson replacing the departed Eric Bell – never performed the song live. In any case, the beautiful 1975 single, Wild One, offers a more substantive blend of rattling acoustic guitars, relentlessly hooky guitar riffs and dewy-eyed Celtic romanticism. In concert, Lynott would introduce it as “a song about running away”, alluding to the fate of the Wild Geese, the 30,000 Irish soldiers who left Ireland to serve in continental Europe following the Treaty of Limerick in 1691. On a more intimate level, it sounds like a message relayed from the heart of his childhood, sent to his free-spirited mother across the sea. “Wild one, won’t you please come home / You’ve been away too long, will you? / We need you home, we need you near / Come back wild one, will you?”

In March it will be 40 years since the release of Jailbreak. While at least half of this landmark album – especially the title track – could justifiably claim a place in any Thin Lizzy Top 10, the position of The Boys Are Back in Town is unassailable. A game-changing global hit in the summer of 1976, the band’s signature tune is a deceptively complex kind of rock anthem. Brian Downey’s snappy shuffle keeps the whole thing swinging, while the crunching power chords underpinning the interlocking guitar lines have an unorthodox, almost jazzy joie de vivre. It is both a song of experience and a piece of acute observation. Lynott pulled inspiration from his own increasingly macho adventures, but the song also pays tribute to the Quality Street Gang, a bunch of ne’er-do-wells who frequented his mother’s hotel in Manchester, as well as the patrons of the Rainbow Bar & Grill on Sunset Strip. A song about storytelling as much as it is a song telling a story, it recognises that the most enduring legends aren’t created in the doing but in the recounting. In urging us to remember “that time down at Johnny’s place” and “that chick that used to dance a lot”, Lynott heightens his showreel of Friday night frolics to the realm of folklore.

The flipside – both musically and emotionally – to the weeping blues of 1974’s Still in Love With You, this 1976 single portrays Lizzy and Lynott at their leanest and meanest. Though it began life during the rather fraught sessions for Johnny the Fox as an acoustic ballad, reminiscent of Stand by Me and, according to a conversation I had recently with Brian Robertson, “really fucking morbid”, the band transformed it into a concise and punchy vindication of their new-found status as major players. Listening to the 137 seconds of Don’t Believe a Word, it’s easy to understand why punks loved Lizzy. Nothing is wasted. Lyrically, it’s Lynott at his least ingratiating – not street-guy tough, but emotionally ruthless. An unflinching mea culpa, it’s an anti-love song that sacrifices any songwriter’s greatest weapon – the contrivance of sincerity – in favour of a more unpalatable truth: “Not a word of this is true.”

It’s hard to think of any other rock band of the 1970s in possession of the lightness of touch to write and record a song like Dancing in the Moonlight. A fond, finger-clicking recollection of teenage misadventure on the streets of south Dublin, it’s an affectionate homage to Lynott’s long-standing love of Van Morrison’s blue-eyed soul, with more than a passing nod to Bruce Springsteen and the E Street Band. Lynott was not entirely sure of the track, which was released at the height of punk – he insisted that the hard-driving Bad Reputation be released as a double A-side to avoid accusations of softening up – but it was a timely reminder of his most enduring gifts. He was a pop craftsman when it came to mixing mood and melody, a soulful singer of rare versatility, and a lyricist capable of flinging in exotic twists at will. The line about getting “chocolate stains on my pants” is typical, both touchingly innocent and leeringly suggestive. It was recorded in Toronto with Tony Visconti, and Supertramp saxophonist John Helliwell overdubbed the deliciously slurpy horn part. Great bass, too.

Between 1976 and 1979 Thin Lizzy were one of the greatest live bands in the world, giving everyone from Graham Parker and the Rumour to Queen a run for their money when they shared bills. This version of a Jailbreak album track, taken from the peerless Live and Dangerous album, is almost impossibly exciting. (The question of how “live” Live and Dangerous actually is has long been debated. When I interviewed producer Tony Visconti for my new biography of Lynott, named after this song, he said: “What you hear on the average track on that album is a fixed vocal, most likely a replayed bass part, and mostly the original guitars and drums. I know this to be true because I was in the control room at all times.”) With its dust-blown romanticism and irresistible descending riff, Cowboy Song became an instant highlight in Lizzy’s live set, performed while a spotlit mirror ball showered desert stars around the auditorium. One of several tracks from Jailbreak in which the protagonist vaults over accepted social boundaries, it depicts the touring rock’n’roller as the modern-day vaquero, a high-plains existentialist dedicated to living a life without ties. It’s so vividly done you really can hear “the coyote call”.

The only Thin Lizzy studio album to feature the band’s stand-in live guitarist Gary Moore, 1979’s Black Rose: A Rock Legend is the last truly great record they made, and this crunching blues-rocker is an under-appreciated contender in their catalogue. Blurring the lines between fact and fiction, Lynott casts himself as the beautiful loser “sinking slow”, already lost to alcohol and “messing with the heavy stuff”. The singer was by now in the early stages of a heroin habit, and the song’s flirtatious game of truth or dare lends it a morally ambiguous but undeniable sense of drama: when Lynott isn’t relating his bad habits with a kind of grim pride, he sounds resigned and a little frightened. Engineer Kit Woolven recalls him singing Got to Give It Up in the studio with a brandy in one hand, a spliff in the other, and a few lines of cocaine within easy reach. Moore’s bluesy opening motif evokes the dark side of all this excess, but the winking disco bass run near the end suggests the good times haven’t turned sour just yet.

Lizzy’s later years offer lean pickings when it comes to great songs, with disorientating line-up changes, solo distractions and drug problems taking an obvious toll. Following the recruitment of Tygers of Pan Tang guitarist John Sykes in 1982, the music leaned increasingly towards NWOBHM, while Lynott’s lyrics tailed off badly, but there remain a handful of moments to savour. This 1983 single, the first taken from Lizzy’s final album, Thunder and Lightning, has all the subtlety of a blow to the back of the head from a blunt instrument, but it’s a powerhouse piece of modern British metal. After Cold Sweat entered the charts at No 27 in early 1983, Thin Lizzy’s scheduled appearance on Top of the Pops was axed when a drunken Lynott told producer Michael Hurll to “fuck off” – twice. Within six months the band was over. Within three years Lynott was dead. “I felt a chill on my backbone as I hung up the telephone,” indeed.

• Cowboy Song: The Authorised Biography of Philip Lynott by Graeme Thomson, is published by Constable on 25 February.