As West Indian migrants sought a new and better life in 1960s Britain, mods began to listen to Jamaican ska, a speedy jazz-tinged shuffle beat. Ska had originated in the early 1960s as a Jamaican twist on black American dance music ("upside-down R&B", the Jamaican reggae guitarist Ernest Ranglin called it). Scooter-riding mods adopted the music as a supplement to their diet of imported American soul and jazz, and soon a taste of Trench Town swagger was brought to inner-city Britain, through such Jamaican groups as the Skatalites, and the Jamaican singers Derrick Morgan and the late, great Desmond Dekker.

Ska was, triumphantly, a Commonwealth music that took hold in Britain's inner cities where Caribbean migration was most dense. My Boy Lollipop, sung by Millie Small with a pert underage suggestiveness, was one of the earliest pop-ska hits. It swept Britain in 1964, and became the year's bestselling single ahead of the Beatles and the Stones. For a while this sort of music brought urban whites and blacks together. By the early 1970s, however, with football "hooliganism" a fact of British life, mod culture had splintered into its skinhead offshoot, which was often seen as National Front fodder. Enoch Powell had evoked images of a race war in his 1968 "rivers of blood" speech, and Britain no longer seemed so tolerant of minorities.

Oddly, given their perceived racial antagonisms, skinheads rarely beat up West Indians (by "niggers" they usually meant Asians, who were seen to be easy targets and lamentably unhip). Ska's driving, dancefloor rhythms appealed to the suedehead's passion for uptempo black music, sharp clothes and short hair. Sometimes, if suitably dressed in Crombies and Trevira suits, Jamaicans were allowed to join skinhead gangs and drink cans of Harp lager with them on Saturday nights in the dancehall (Red Stripe came later). West Indians were seen as less satisfactory when they "acted clannish" or "kept to themselves": in other words, when they failed  like the despised "Pakis"  to assimilate into British culture.

Mod's first choice of music was jazz, Richard Weight reminds us. Miles Davis in particular became a fashion icon for blue-eyed soul brothers everywhere in Britain. The photograph of Davis on the cover of his celebrated 1958 Milestones album  Sta-Prest trousers, button-down Ivy League shirt  became a sort of mod pin-up. Mods ("modernists") were among the first white Britons to embrace west-coast jazz, which had been galvanized by the Birth of the Cool sessions led by Davis in New York from 1949-50.

Soho jazz clubs such as the Flamingo, where Jamaican ska-reggae bands played alongside mohair-clad "modernists" such as Georgie Fame, helped to break down race prejudice in postwar Britain and provided white audiences with an opportunity to encounter West Indians and even (heavens!) talk to them. In Weight's analysis, mod was a uniquely British amalgam of black American and black Jamaican music and European fashions. Soho, where Italians had settled after the war in order to work in ice-cream and confectionery, was a haven of continental mod styles ranging from Gaggia espresso machines to Vespa scooters. The Italian film star Marcello Mastroianni, impeccably dressed in Fellini's La Dolce Vita, was a mod icon, whose world-weary allure and curiously impotent sex appeal conformed to a mod ideal of dandyish (perhaps even homosexual) urbanity.

If mods disdained rockers, says Weight, it was because they mimicked aspects of American popular culture without "creating anything original". Mod, the first distinctively British youth culture, thrived at a time when the empire was played out and moribund; the appropriation of RAF insignia and the union flag was a means to counter the sorry threadbareness of imperial Britain. After the material deprivations of the postwar years (when, as we read in Ian Fleming's Dr No, "people streamed miserably to work, their legs whipped by the wet hems of their macintoshes") came the mod extravagance of Carnaby Street, Mary Quant and Terence Conran's first Habitat store.

Conran was, in a sense, an early mod, who brought a taste of continental design (not to mention duvets) to a newly affluent British public. Weight dilates knowledgeably on mod-inspired films, architecture and design, as well as music. As the 1950s gave way to the 1960s, the taste for Miles Davis and Thelonius Monk was replaced by parkas, amphetamines and Who albums. (Pete Townshend appeared on the cover of the Observer magazine in 1966 wearing a jacket stitched out of the union colours.) Another very English mod band, the Kinks, offered a hybrid of music hall and electrified Noël Coward. Waterloo Sunset, a classic Ray Davies weepy, shows a mod fascination in the vagaries of the English class system and a roseate glow of romance.

Mod was revived in the late 1970s in the Midlands by 2 Tone bands such as the Specials and the Selecter, who fused a pavement-pounding leftist politics with the jolly-up jazz of Jamaican ska. In Coventry and Birmingham it was again cool for whites to have black friends; ska-loving "Cov lads" and their rude boy allies helped to make black West Indian culture synonymous with youth culture in Britain today, where a Jamaican inflection has long been hip even among white teenagers. Mod, well-written throughout, crackles with reflections on fashion, music and film, as these became the giant pop art project of the far-distant 1960s and beyond.

Ian Thomson's The Dead Yard: A Story of Modern Jamaica is published by Faber

Let us leave aside the 1960s for a moment, and acknowledge that for most people who came of age in the UK between the late 1970s and mid 1980s, mention of the word "Mod" should spark at least a few Proustian flashes. There may be memories of a local teenage gang clad in ex-army parkas, or perhaps a recollection of provincial discos always setting aside 15 minutes for a run of songs by the Jam. The more hard-bitten might be transported to the origin of habits that have never left them: the insistence that collars should always be buttoned-down, or a belief that lapels on a jacket must never exceed a certain width. In retrospect, one other thought might occur: that when a London-centred 60s cult was revived circa 1979 and its influence once again rippled through the culture, we saw the decisive stirrings of something now taken for granted  a pop culture that endlessly resurrects and recontextualises the past.

As an adolescent growing up in the far-flung suburbs of Manchester, I was consumed by my first taste of what Mod had left behind, and it changed me for ever: the initial rites included a poleaxed listen to the Who's My Generation (which, even in 1984, sounded like musical gunpowder), my first and only pair of twotone tonic trousers, and a dreamed-about trip to Carnaby Street, or what remained of it. But what my friends and I were doing had almost nothing to do with Mod's rarefied beginnings, crisply explained in Jonathon Green's oral history Days in the Life (1988) by the journalist David May. "Mods were always intellectual," he said. And at the start there "was always a large gay element in it. On Saturday afternoon we'd go to get our hair done in the women's hairdressers. Then we'd go out in the evening, dancing  We didn't fight rockers, we were far more interested in some guy's incredible shoes, or his leather coat. But underneath this, one did read Camus. The Outsider: there it was, it explained an awful lot. A sort of Jean Genet criminal lowlife was also important." As a more succinct statement of what it was all about, I have always loved the late Mod pioneer Peter Meaden's famous quote  reproduced on the sleeve of the Who's 1973 Mod-opera Quadrophenia  about "clean living under difficult circumstances".

Uncertainty clouds both Mod's origins, and its legacy. The word was definitely short for "modernist", and initially at least, the face-off between "trad" and "modern" jazz was central to the cult's self-understanding. Up until around 1962, its disciples probably numbered no more than 150, resident in east and north London, and fond of enjoying themselves in Soho, refreshed by such go-faster drugs as Dexedrine and Drinamyl. West End clubs The Scene and The Flamingo were important  as, at various points, were sartorial items including Brooks Brothers shirts and Clark's Desert Boots. But much of the rest is unclear, particularly the almost unfathomable series of coincidences and superficial similarities that may or may not tie together Mod's clandestine beginnings, and scores of later happenings.

In other words, what could possibly link 1980s suburban oiks in Fred Perry shirts to sharply dressed 1960s existentialists? This book, written by an academic, attempts an answer, contending that Mod was not only "the first distinctively British youth culture" but "a popular form of modernism  that stream of creativity in Europe and America that began in the early 20th century as an avant garde reaction to mainstream aesthetics, morality and politics". Its 400-page text goes from the 1950s to the present day, and mentions a sprawling array of people and cultural touchstones: Terence Conran, Mary Quant, the Beatles, Michael Caine, the artist Bridget Riley, David Bowie, 1970s Northern Soul, 1980s football-following "casuals" and more. The book does not convincingly tell the story of the original Mods  to all intents and purposes, the only people worthy of the term  perhaps because its ambitions are much loftier, something embodied in its subtitle's citing of a "very British style".

But such a wide focus  "Perhaps  we are all modernists now," Weight ends up suggesting  creates dire problems when it comes to coherence. There is almost no sense of a story unfolding  instead, Weight opts for a scattershot narrative, brimming with second-hand quotations, a bit like an undergraduate dissertation ("As George Melly recalled  As Dick Hebdige has argued  As the American critic Ted Polhemus explained"). The writing manages to convey roughly what he is getting at: a sensibility whose inspirations fell between mainland Europe and the US, and a drive to transcend class via an attachment to style and what the modern vernacular would call aspiration. But he gets so lost in the big picture that crucial details are almost forgotten. The sole discussion of the Mods v Rockers seaside disturbances that marked the cult's high-water mark of visibility and also the moment at which it lost all connection to its origins totals a few paragraphs, and comes in a chapter on the 1970s. There is a chronic shortage of anecdotes  which, in the case of a phenomenon so driven by remarkable individuals, is a real shame. There are also errors of fact, and interpretation: "AirWair" is not an eight-hole variety of the Doctor Marten boot but the generic brand-name of its air-cushioned sole; if you think the Jam's "Town Called Malice" "celebrated family life", you have probably never heard it.

Plenty of other things are either omitted, or underplayed. Aside from the specifics of jazz, rhythm'n'blues, Italian suits and the rest, what arguably defined pure Mod was a fevered consumerism, whereby what was in or out could change drastically in a matter of weeks. The cult was also almost ludicrously hierarchical, so that an inner circle of "Faces" held themselves to be very different from mere "Tickets" or "Moddy Boys". Small wonder that the most devoted Mods seemed to have no countercultural aspect whatsoever: "A lot of these boys went off and did jobs like bank clerks," one ex-Mod later recalled, "and their managers thought they were fantastic  I used to go to work and I was better dressed than my boss by a long way."

In fact, what gets lost in Weight's rather forced attempt to identify a "modernist" sensibility running through whole swaths of post-60s culture is something much more simple: the idea that the Mods were on the cutting-edge of modern capitalism, trailblazers for the latter-day high street notion of "fast fashion", and that very profitable practice by which companies market themselves via carefully chosen figureheads  and the herd runs off in hot pursuit.

The 14-year-old me would wince at the cynicism of that observation  and he would probably have a point, because it does a disservice to Mod's seductive and magical lifecodes. They probably defy rational explanation, better understood via a clipped electric guitar chord or the fold of a shirt-collar than any text. But to be reductive about it, the Mod ideal boils down not just to a kind of neurotic selfrespect, but an emphasis on sharpness, an attention to detail, and everything being just so. And in that sense, this rambling book is so unlike its subject that it ends up missing its target, by miles.