The early nightclub your boss will love

First held "just for friends" at Brick Lane's 93 Feet East in 2001, James and music partner Giles Smith had no idea Secretsundaze would end up a summer institution, with Sunday parties not just Ibiza-style, but actually in Ibiza, Barcelona, Berlin and Croatia as well as London.

They've also established a reputation for breaking underground DJs, unique open-air venues and a 6,000-plus fanbase of clubbers eager to party through the weekend. It's only 7pm on a sunny, late summer Sunday, but a dedicated crowd, each paying a £15 entrance fee, have been arriving since 4pm and they're dancing hard to deep house beats blasted out by Berlin-based headliner, Dixon.

Most are in their late twenties and early thirties, good-looking and cool, but not achingly Shoreditch-trendy. The lack of 5in heels is proof this all-dayer is about relaxed socialising and having a good dance.

As the sun sets and the natural light-filled room darkens, the atmosphere gets edgier, evoking Ibiza's infamous DC10, complete with a group of pushy Italians. The bar is under a vaulted arch and enough staff are on hand to ensure a fast supply of Red Stripe (£3.50), vodka/gin and mixers (£4.50) and Red Bull (£3). Chatting to clubbers, I realise Secretsundaze has become the perfect party for ravers who don't want to face work after a non-stop weekend. "We used to get lots of all-nighters, but not so much these days," James agrees. "All-dayers are much more suitable for most people."

I speak to a BBC researcher, an events organiser and a garment technologist, all hangover-free, all here for the music and definitely not into a super-late-night, booze-fuelled Sunday. Holly from music label Demon Records tells me she wasn't even out last night, while student and techno DJ Rich Evee says he is a big fan of smaller east London parties like this, much preferring them to superclubs like Fabric and Matter.

A pretty stockbroker and her best friend agree, and while assuring me they are "just here for the music" soon admit to checking out the eye candy, and it's not long before a "spilt" drink has them flirting with two guys at the bar.

An old Victorian warehouse, Village Underground is a huge, rectangular space with exposed brickwork and a 10 metre-high ceiling. Used for exhibitions and installations, it has old Tube carriages on the roof, used as studios. When I arrive the outside wall is being spray-painted with large eyeballs by graffiti artists Jim Crayon and Sticka for an anti-drug-driving campaign. "Secretsundaze was the first to do a party at Village Underground back in 2006. We went really overboard with huge palm trees!" Clare Dover, one of the organisers, laughs. "This is one of the few all-indoor spaces we use. We thought we'd better play it safe — last year Dixon was rained off at the Ministry Of Sound courtyard." (Having said that, they are taking a risk with their summer closing party, in that very same courtyard, on 11 October.) As Dixon, fêted for his skilful set programming, drops a favourite tune — his own Lykke Li remix — I bump into a music lawyer pal with her gang of Secretsundaze veterans, including DJ/producer King Roc. We hit the dance floor and squeeze to the front to get the best out of the huge sound system thundering through the floorboards, and entranced by the venue's only decoration — a huge disco ball in the centre of the room. A Secretsundaze mascot, the disco ball has travelled to venues far and wide, including a gruelling two-day drive to Barcelona for Sonar.

Tonight, captivating graphics are projected on to the ball, perhaps explaining the low, low lighting — it's so dark a doorman is guiding smokers in and out with a torch.

At 10pm, half an hour before closing time, a couple of friends drop in for a beer. Having spent the day at Kew Gardens they are overwhelmed by the full-on club atmosphere — it feels like a hardcore 4am. We stand outside in the smoking area amid the chattering buzz before heading home. It's just gone quarter to eleven. I've had a few drinks, a good dance, a catch-up with pals and the Tube's still running. A perfect night? Not far off! If I didn't have work in the morning, it might just be.