Marc and the Mambas, Royal Festival Hall, London Elizabeth Fraser, Royal Festival Hall, London

In 1982 and 1983, while Soft Cell were artfully falling apart, Marc Almond was living with his pet snake in a still-sleazy Soho, sneaking out after dark to hang with the Goths at the Batcave. Mentally, however, as he recalls in his autobiography Tainted Life, he was residing in a "tranquillizer universe and smack heaven". In this state he launched his first side-project, an ad-hoc collective called Marc and the Mambas, whose untitled debut consisted, he admits, of "the deluded ramblings of self-indulgence fuelled by too much acid".

Their second effort was something else. Far from running on empty, the drug-damaged Almond followed the road of excess all the way to the palace of wisdom. Taking the torrid passions of Spanish culture as its inspiration, Torment And Toreros is a double album of which Almond remains proud.

His label Phonogram considered it commercial suicide, and it received mixed reviews – Almond attacked one Record Mirror critic with a whip – but a young Antony Hegarty praises its courage in his introductory speech at the Southbank, and tells us it was "a blueprint for me, as a queen". When Antony was approached to curate this year's Meltdown Festival, a staging of Torment and Toreros was the first idea that came to his mind.

And so, to the sound of thundering timpani, an imperious Almond strides out in Andalusian sombrero, black silk kimono, and Cuban heels. He throws a flamenco pose, and stamps into a show which leaves everyone feeling that they have seen something very special.

A sculpture of a bull's head waits atop a grand piano. Early in the first act, during Jacques Brel's "The Bulls" he will wear it as a mask while, overhead, images of dancing senoritas alternate with photos of slaughtered bulls. Though opposed to animal cruelty, Almond is both repelled and attracted by the horror of a bullfight and the raw sexuality of its symbolism. Torment and Toreros draws parallels, implicit and explicit, between matadors and military massacres, prostitution and addiction, masturbation and suicide.

It's an album that revels in squalor. "Don't forget, little snakes," Almond wrote on the sleeve, "if you're going to wallow, wallow deep." There are such lines as "The entrance to your heart is just another old hole" ("Little Book of Sorrows", for which Hegarty joins him in a stunning duet). And, on tracks such as "A Million Manias", it's painfully self-aware: "The taxi driver starts to sing one of my songs/The one I like the least/He says 'That's the only one I like'/My face cracks …".

Soon after the making of Torment and Toreros, Marc Almond temporarily "retired". Nights like this make you grateful that he reconsidered.

Step into any of a million lamplit student bedrooms in the 1980s and you'd hear the music of The Cocteau Twins, hanging in the air as heady as incense. The Scottish trio's sound was based on the alchemy between Robin Guthrie's emerald cascades of reverbed guitar and the enraptured voice of Elizabeth Fraser, her unintelligible, seemingly nonsensical syllables flowing in ecstatic peals.

In the 15 years since The Cocteau Twins disbanded, Fraser has been a reclusive, stage-shy figure. Barely illuminated by an autocue tablet, her hair, no longer russet, is now as silver as her skirt, and smoothed down into a pageboy crop, giving her the appearance of a nervy deputy headmistress at the annual ball.

In front of an adoring and strangely rowdy Meltdown crowd – she's handed bouquets, but also receives at least two loud marriage proposals and a simple, quizzical "Where have you been?" – she delivers a set split 50/50 between celebrated past and solo present. Her voice is timorous, creating a nightmare but still possesses a dazzling range. One whoop, on "Suckling the Mender", skips way past top C. The problem is that her band, all former members of Spiritualized, never replicate The Cocteau Twins' bejewelled majesty, but rely on watercolour washes of synth and the kind of drumming you hear in a History Channel documentary.

The new stuff has its moments. "Make Lovely", with vampiric ex-Genesis guitarist Steve Hackett guesting, is almost a madrigal. And classics such as "Cherry Coloured Funk" and "Donimo" scale their old heights. But "Pearly Dewdrops Drops", the Cocteaus' closest thing to a hit single, falls flat.

The religious experience expected by her devotees never quite materialises. Perhaps Fraser has forgotten what Marc Almond has always known: if something's worth whelming, it's worth overwhelming.

The festival season jogs on, and next weekend the Welsh hillsides will echo to the sounds of Dexys, Mogwai, Van Morrison, Metronomy, Feist, Scritti Politti and dozens of others at the Green Man Festival, Glanusk Park (Fri, Sat, Sun). Meanwhile in the Midlands, Summer Sundae brings Katy B, Adam Ant, PiL, Patrick Wolf, Billy Bragg and tUnE-yArDs to De Montfort Hall & Gardens, Leicester (Fri-Sun).