Nobody drew the NWOBHM jacket and nobody sold the first one. Lay a new estate out with concrete paths at right angles and inside a single summer a bald brown line runs diagonally across the grass from the corner of the flats to the bus stop, cut there by a thousand pairs of feet that never met and never agreed about anything, until the council's only honest option is to tarmac what is already underfoot. The uniform of the new wave arrived by that route.
The Barnsley five who put both of its materials into a song title in September 1981, and who then had to walk out in front of a hall full of people dressed in the results, were Saxon. What the wave wore between 1979 and about 1981 came together with no designer, no stylist and no single shop behind it, out of two garments from two entirely different classes of origin worn one over the other, plus a handful of small metal objects that stripped the last of the cheesecloth and the loon pants off the British club floor. It was assembled. It was never chosen.
How the wave rose, who named it and what it did to the charts is set out in the longer account. The clothes are a separate question with a separate answer, and most of that answer is about money.
Where the nwobhm jacket came from
Denim was already in the wardrobe, and that is the whole reason it won. Sold across the British high street through the seventies as workwear long before it was sold as anything else, a cotton jacket cost a fraction of what a night out did, survived being sat on in a car park, and had been standing dress for the long haired rock audience since the Deep Purple and Motörhead crowds of a few years earlier. Nobody had to be persuaded into it. Nobody had to save for it either.
Leather came from the other direction entirely, and it came down off the stage. The man whose kit the whole wave copied without once being able to price it was Rob Halford, who had put Judas Priest into black cowhide, a peaked cap and chrome studs in 1978, and every photograph of a British band from the two years that followed shows somebody trying to get within reach of that silhouette on a fraction of the budget. The look was free to admire. It was not free to buy.
A coat that has been through three brothers carries three sets of repairs, and a tailor can date each one by the thread and the stitch length without being told a thing about the family. The wave's inheritance reads the same way. The denim is the older brother's, worn soft by a decade of rock crowds; the leather is borrowed from a stage that had owned it for eighteen months; the studs are the newest work on the garment by a distance.
Denim by default, leather by ambition
The arithmetic decided nearly everything else. A hide jacket from a London maker such as Lewis Leathers, which had outfitted British rockers since the 1950s, stood at many times the price of the cotton one on the next rail. Even its own riders' club paid for a jacket in instalments rather than in one go, and a fifteen year old on a Saturday wage in a shop or on a milk round could reach the full kit only the same way, one item a birthday, or not at all.
So the cheap garment was made to carry the expensive one's meaning. Studs punched through cotton, a wristband, a belt and a length of chain did to a denim jacket what almost nobody in the hall could afford to do properly in hide, and by common consent that hybrid, cotton below and chrome on top, is what the wave actually looked like rather than the head to foot leather of the press photographs. The rich version existed. The poor version filled the halls.
The cheap garment was made to carry the expensive one's meaning.
The rest came off market stalls and out of army surplus shops, which is why so little of it matches from one photograph to the next. Nothing about the assembly was national, nothing was co-ordinated between one town and the next, and the results still landed close enough across Britain that a stranger walking into a strange venue in 1981 could read the whole room inside three seconds.
What was on the floor, 1979 to 1981
Underneath everything was a band shirt, over it the denim, over that the hide if a job or an older brother had produced one, and the jacket was as often sleeveless as not. Below the waist it was jeans, tight, and white sports trainers, which is the detail that dates a British photograph faster than any haircut, because the American bands of the same years were wearing boots and the crowd in a town hall in Yorkshire in 1980 was not.
"Denim and Leather", the title song of the album Carrere released in September 1981, works best read as an inventory. It names the two materials, it names the seven inch singles and the halls and the people standing in them, it moves at a marching tempo with the chorus built to be answered rather than admired, and it was written by men who had spent four years on the other side of that barrier. It is a roll call. It is not a fashion note.
The stage wore what the floor wore

Here is the thing the older acts could not do. A Kiss costume had to be built, fitted and maintained by people on a payroll, and nobody in the audience was ever going to walk out of the building wearing one, whereas the bands of the new wave went on stage in clothes bought where their audience bought them, which is attested by every photograph of the period in which the front row and the band are indistinguishable apart from the instruments.
The London trio whose self-titled album Bronze put out in 1980, and whose title song still gets sung back by rooms full of people who were not born when it was cut, were Angel Witch, and the photographs from that year show three men in exactly what the queue outside had on. The London four who spent 1980 opening for Motörhead, and who wore the same denim and the same chrome without treating any of it as a statement, were Girlschool. The uniform was never gendered. The press coverage of it was.

The Newcastle three who broke that rule on purpose, turning up in sports padding and a goalkeeper's gloves while everyone around them stood in cotton and hide, were Raven, whose Rock Until You Drop went out on Neat in 1981 at a speed the rest of the wave had not yet reached. The costume was a joke the band told well. It is also the exception that shows how hard the rule held everywhere else.
A stage costume is something handed to you at the door of a dressing room. This wave had no dressing rooms worth the name, so it went on in what it had arrived in.
Declan Rourke, KaosMetal
Where the uniform went
It left the country on tape and came back on record sleeves. The young American and German bands who bought the wave's singles by post through 1981 and 1982 copied the clothes off those sleeves along with the riffs, and a denim vest over a leather jacket is still standing dress on the European festival circuit four decades later, worn by people who were not alive when Carrere pressed the record that named it.
What changed is the direction the money runs. A jacket that once had to be assembled out of a market stall, an older brother and a year of birthdays can now be bought finished at a merchandise stand in one transaction, which is a convenience and a loss in the same movement, because the whole use of the original was that it recorded how long its owner had been at this. A bought uniform says what you like. An accumulated one says how long.
The films that took a camera into those car parks and those queues, and that hold more of this material than any written source does, are gathered under the NWOBHM documentaries. Everything in them is second hand, badly lit and out of focus at the edges. It is still the best evidence there is.