To dubstep or not to dubstep, that was the question perplexing the nearly 5000 metalheads jammed into the Brixton Academy to see Korn.

Although the four days of Norway’s 15th by:Larm Festival were dominated by the presentation of the second annual Nordic Music Prize, there were plenty of other distractions: a sobering tour of Norwegian black metal’s infamous sites, a talk by legendary Nigerian drummer Tony Allen, what felt like millions of shows in millions of venues, and weather confounding all expectations of what Oslo ought to be like in February.

Justice – pronounce it “Joosteece”, for they are as French as they come – deconstruct the opposition between style and substance. Everything about them is preposterous, from the hipster facial hair via the rock-pig antics in their A Cross The Universe tour “documentary” DVD to the way that almost the entirety of their musical palette is cribbed from their countrymen and close associates Daft Punk.

It must have been difficult for Mexican acoustic instrumental guitar duo Rodrigo Sánchez and Gabriela Quintero to know where to go next. Initially discovered in Dublin as high-end buskers, they’ve built a career on energised acoustic pyrotechnics, combining complex Hispanic flourishes with heavy metal tics. It’s an invigorating concoction, especially live, and eventually they were courted by Hollywood, writing pieces for Puss in Boots and the last Pirates of the Caribbean film.

Of all the unlikely and incompatible collisions of genre imaginable, thrash metal with clubland trance must be pretty near the top of the tree. One is beefy, roaring, angry and punctuated by vocals akin to a dyspeptic troll burping, the other is electronic, poppy, air-headedly euphoric and can contain divas wailing banalities. This combination, however, was the horse a young St Albans band chose to ride for their 2006 debut single “Sorry You’re Not a Winner”.

For about an hour in Hammersmith last October it seemed that all 2011's new music had coagulated into some kind of supernova and was exploding on stage. There were two drum kits, nine musicians, and a nerdy, lanky man singing like an alien. The support act had told us to expect something special and was it ever: Bon Iver’s extraordinary live reimagining of their bucolic, eponymous album took in folk, prog, soul, metal and avant garde. It also pretty much embodied my review year.

In the mid-Nineties, America had a bit of a moment with electronic dance music. The most emblematic sign of this was The Prodigy’s Fat of the Land topping the Billboard charts in 1997. The truth was, however, that despite inventing house music and techno, en masse nationally they didn’t really get rave culture. The US liked their electronic dance stylistically performed as close to a KISS concert as possible. They liked it, in other words, to be rock’n’roll.

If anyone tells you that Deep Purple’s Concerto for Group and Orchestra (1969) wasn’t a masterpiece then they’re an idiot. In fact, it was, more or less, the only successful use of an orchestra with a rock band ever. Now, 40 years on, a pensionable Purple have hit the road again with a full symphony orchestra. But they’re not playing the Concerto. They’re playing their hits. Critically, they’re performing them without founding keyboardist, Jon Lord, and guitarist, Ritchie Blackmore.

Lemmy Kilmister (b 1945) was born Ian Fraser Kilmister in Burslem, near Stoke-on-Trent, Staffordshire, but spent his formative years in Anglesey. His father, ex-RAF padre, left when he was an infant and he was raised by his mother, who worked as a librarian, and his grandmother. He was interested in rock and pop from an early age and formed various local bands, most successful of which were The Rockin’ Vicars who had a CBS recording contract.