For most people’s 40th birthday celebrations, they might get a few friends together, rustle up a cake, and toast to another turn around the sun. But when musician Lail Arad realised the stars had aligned with her beloved Joni Mitchell's own 80th birthday, she knew she had to mark the milestone moment with something special.

This mixed reality concert is simultaneously a dimension juggling conundrum, a philosophical puzzle, and a fascinating insight into what the future might hold. Composer Ryuichi Sakamoto – whose influences included Bach, John Cage and David Bowie – died in March last year, but still lives on in this curiously moving virtual event in which his performance was captured by 48 cameras at 60 frames a second.

A dystopian present. Sirens ring out across the city. Firefighters rush to the wrong locations. A man insists on entry to a big house.

He’s not selling anything, so he can’t be an arsonist can he? His friend turns up and she’s pretty upfront about her intentions – and the barrels of petrol in the attic rather give the game away. But the wealthy homeowner, so ruthless at work, is so polite at home, the coming conflagration all but accepted as a matter of… manners, social convention, apathy?

London’s Roundhouse is a very special venue. For decades the circular shed, with its elegant ironwork supporting structures has hosted a wonderful and varied series of performances. Like a great cathedral, the space has a hallowed feel about it. The culmination of a sold-out UK tour, PJ Harvey’s exquisitely paced and passionate set, as much pagan ritual as perfect entertainment, makes the most of this womb of a space.

Anaïs Mitchell should be a star: she sings like a dream, oozes presence and charisma, and writes songs of classic simplicity, poetry and depth. Her other outstanding quality is a natural modesty and a delight in just being herself on stage, and sharing the joys of music-making with her fellow-musicians and the audience.

Fatoumata Diawara knows how to please: with a winning and innocent smile, she wins the audience over in a matter of seconds. She has a vocal style all of her own: in her first song, “Don Do”, a quiet and meditative prelude to the boisterous show that follows, she seduces with sensual textures and a slight rasp unique among West African women singers, and which owes as much to jazz and gospel as to the traditions of her musically-rich country.

John Grant’s entry onto the stage was unobtrusive, appropriate for a set-up that consisted of just a grand piano and an electronic keyboard (with accompanying keyboardist). He began with similarly unadorned songs, the ballads that peppered the start and the end of his set.

While bands such as The Birthday Party, Siouxsie and the Banshees and, especially, Bauhaus had a hand in inventing goth music at the start of the Eighties, it was The Sisters of Mercy who defined it. Their combination of black clad cowboy shtick, mirror shades and dry ice worked a treat. In recent years, there have been rumours that the band’s live shows are less than impressive, mentions of a tendency to focus on unreleased material while dressed in leisurewear.

Emmanuel (Anthony Ofoegbu) runs Three Kings Barbers in London. His assistant, Samuel (Mohammed Mansaray), is the son of his erstwhile business partner, who is currently in jail. Emmanuel is boss, surrogate father and — occasionally — verbal punching bag: Sam is a whizz with the shears and just as cutting with his tongue.