Scrutinising the set times as we arrive at the venue’s entrance produces smiles all round. N’fa is about to take to the stage! We bound up the stairs in delight. The ex-1200 Techniques frontman (known then as N’famas) is certainly infamously hot, both visually and aurally. He looks dapper in his trilby hat and shares, “We haven’t jammed together for ages. I’ve been away for a few months”. It doesn’t show. An atmosphere like a homecoming permeates the room and N’fa gives a shout-out to his cousin in the crowd. His cuz beams excitedly and the family resemblance is striking – you’d swear it was N’fa incognito in a dreadlock wig. The crowd happily chant back, “We came to par-tay!” and a suspicious amount of oestrogen dominates the nosebleed section.

N’fa’s DJ sports a black T-shirt emblazoned with a technicolour Storm trooper helmet and he’s definitely feeling the vibe: he busts some serious grooves and a sly grin creeps across his face. ‘Cause An Effect’ is true to the song’s title and devastates the room. Inventive flow is trademark N’fa – “Put ‘em up like a dirty cop told you to freeze” – we’re officially under arrest. N’fa and his crew could have made us sway “Left, right, left” all night long. There should be a picture of him next to the word ‘repraZent’ in the dictionary.

During the relatively long set-up time the venue packs out. Five microphones are evenly spaced across the front of the stage: an auspicious teaser of what’s to come. Enter Katalyst (Ashley Anderson on his library card). He builds the suspense, “We’re ready. Are you ready?” Our cheered response doesn’t satisfy, “Are you sure?” One louder this time. He gauges via a show of hands how many crowd members have purchased his latest album ‘What’s Happening’. The response is overwhelming but I’m sure a few sneaky downloaders/burners falsely claim to have invested their hard-earned.

The first collaborator to be welcomed to the stage is Australian Jamaican MC Ru C.L. He bursts forth and owns it with ‘Step Up’. He don’t need to, he’s already there. The dollar sign on his cap is the ultimate bling. Next up to one of the mics is New York based soul sensation Stephanie McKay. The crowd roar is deafening and nonstop. McKay has worked with the likes of Mos Def, Talib Kweli, Amp Fiddler and Geoff Barrow and now she performs a number from Katalyst’s ‘Dusted’ album – ‘Take Me Over’. Her joyous persona is akin to Sharon Jones (of the Dap-Kings fame) and she follows on with her view of ‘What’s Happening’ – ‘Say What You Feel’.

The first single lifted from Katalyst’s revered ‘What’s Happening’ album is ‘All You’ve Got’ (the one with the cool skater video and “doo-doo-doo” chorus). Ru C.L, N’fa and then J-Live share microphone honours and raise the roof on proceedings. J-Live’s tone resonates and he announces, “Katalyst is in the space!” We’d hardly noticed given the plethora of talent onstage but props to him for supplying the beats. This is not the sort of night to attend without your heart tablets, the guests just keep on raising the bar.

The quivering strings in ‘How Bout Us’ elevate Steve Spacek’s vocal to a level of enchantment. No wonder Giles Peterson from BBC1 has called him “the voice of modern soul”. He channels a definite Marvin Gaye-ness. J-Live’s ‘Killing Ya Self’ is killer. Lyrical content “You’re selling poison straight off the record store shelf” does not apply to Katalyst.

The only segment of the night that seems to wane is when Adalita (Magic Dirt) takes to the stage for ‘Bladewalker’. She’s a foxy vixen behind the mic that much is true, but the crowd doesn’t seem to be into such disparate genre-bending. Material from ‘Manipulating Agent’ brims with psychedelic energy – perfect sounds to be soaked up by lava lamplight. ‘Showtime’ continues and the heavenly presence of McKay reappears for the rowdy punters.

Without any hoo-ha, the posse leave the stage which is unexpected. At 1.30 am the cast of thousands file back on for an encore and absolutely kill it. On our way past the cloakroom/merchandise area, I’m pulled aside by J-Live. He requests a ‘hat swap’ and we try each other’s on for size. I would have happily traded for his patchwork flat-hat except mine looked the size of a fascinator on his noggin!

For those who think hip hop belongs in the ghetto, think again. It’s a rare privilege to see all these ridiculously talented souls sharing a stage – testament to Katalyst’s pulling-power. Tonight’s crowd reaction blew off the Richter scale. What’s happening? Katalyst, that’s what!