In the Beginning there was Punk.
Influences on goth stretch far further back, to Bowie, the Doors and the Velvet Underground, but the punk explosion of the mid/late 70s created the essential background for goth, in both music and fashion.
In the aftermath of punk in the late 70s and early 80s a bewildering variety of new and re-invented musical styles began to crop up, and around 1978-9 a style began to appear which the press had by late 1979 started to call "gothic".
The creators of this musical style (who were themselves influenced by the likes of the Velvet Underground and Bowie) were essentially Joy Division, Siouxsie and the Banshees, Bauhaus and UK Decay.
The first Banshees album ("The Scream", November 1978) and the first Joy Division album ("Unknown Pleasures", June 1979) laid much of the template for goth, with a notable absence of loud punk guitars and the emphasis on the rhythm section instead, along with a stark, hollow sound.
However, the first band who cannot be comfortably classified as anything other than goth were Bauhaus, who released their first single, "Bela Lugosi's Dead", in August 1979. The Banshees could be considered punk, The Cure could be considered New Wave, Joy Division could be considered post-punk, but Bauhaus were unmistakably goth in music, looks, lyrics, art and style right from their first single. In many ways they were the archetypal goth band.
Around the same time as Bauhaus were emerging, UK Decay were discarding their punk roots and developing their own independent "gothic" sound. Although never as popular as Bauhaus, Joy Division or the Banshees, UK Decay were far closer to the second wave of goth bands and were an important influence on them.
By 1980/81 a new wave of goth bands were beginning to emerge- Danse Society, Play Dead, The Sisters of Mercy- and the Cure had abandoned their New Wave sound and created a unique "gothic" sound of their own. In February 1981 Abbo from UK Decay tagged the new musical movement "gothic", but it was to be another year or so before the movement really got going.
The crucial period for the development of goth into a fully-fledged subculture is mid 1982 to mid 1983, with particular emphasis on October 1982 as the month the new movemenet suddenly started receiving major media attention.
In July 1982 the Batcave opened up.
This was at first envisaged as a club for people who were fed up with the commercial direction of New Romantic and wanted something new and darker. At first it played glam and electro music, but several early goth bands also played there and the playlist gradually became more goth.
The Batcave thus became a major rallying-point for the emerging London scene and also attracted a lot of media attention, which in turn spread the idea of a new subculture around the country. In the wake of the Batcave, similar clubs opened around the country, and the Batcave itself went "on tour", giving goths outside London somewhere to gather.
Thus, whilst offering little in the way of music (apart from ASF and Specimen), the Batcave had a major impact on goth fashion and popularity. Essentially, it added a huge dose of "glam" and media attention to the emerging subculture.
Then in October 1982 Bauhaus released "Ziggy Stardust", which became a big hit (#15 in the UK charts) and put them on Top Of The Pops and the front cover of Smash Hits (October 1982).
The new wave of goth bands also began receiving serious media attention, with Southern Death Cult getting a front cover on the NME (October 1982) and Sex Gang Children getting a front cover on Noise! (also October 1982).
Following this, two articles in early 1983 focussed on what was by then unmistakably a separate movement.
In February 1983, Richard North of the NME hailed it as Positive Punk
A month later, Mick Mercer wrote a similar article about the new bands in Melody Maker (though his choice of bands, like Danse Society, was a lot more pertinent).
Meanwhile, the movement was getting a name- the term "gothic" had been floating around for a while, and the name was fixed to the emerging scene by two of the most important bands in it: Andi, the lead singer with Sex Gang Children, was tagged "Count Visigoth" and his followers tagged "goths" by Ian Astbury from Southern Death Cult. Dave Dorrell from the NME then overheard them using the term and it passed into journalistic use.
In October 1983 Tom Vague ws referring to "Hordes of Goths" in Zig Zag magazine, by which time both the term and the subculture were firmly established.