It's 3am on Sunday on South Great George's Street in the heart of Dublin's so-called "creative quarter."

Girls in tight skirts and vertiginous heels totter to the kerbside hailing taxis - knock-off Chloe handbags swinging from bare shoulders.

They are on their way home to the south and north city suburbs or staying with friends in dockland apartments. Their night is over - bar the morning hangover yet to come. Nothing that a couple of Solpadeine and a bottle of Lucozade can't put right.

But others are lagging behind on the street. They know the night isn't over yet - if they can make the right contact.

Welcome to Dublin's underground club scene where those "in the know" and with the right connections can party like it's 1999.

They are "private" parties that have an entry fee. Drinks are served discreetly from behind a curtain like a Prohibition-era speakeasy.

You can smoke inside with impunity. There are no outside smoking areas where raucous noise might alert neighbours and the authorities that 200 people are partying until 8am and beyond. Inevitably drugs are proffered - uppers, downers, ecstasy, cocaine. The paying "guests" are picked with care with the organisers cruising legitimate venues from 2am offering "wristbands" for an "after party" at another venue on the other side of the Liffey.

The new scene has emerged in the last year or so but has gained a new impetus in recent months - perhaps an inevitable by-product of better times for Generation Y.

My first experience of Dublin's burgeoning after-hours clubs was on the Sunday of the May bank holiday weekend.

Out with friends, I was approached on the dance floor to purchase a 'wristband' to keep the party going at a separate venue hosting an after party.

For €10, I thought "what the hell". I had heard a lot about these venues and I was curious to see what exactly went on. In all honesty, there was a certain gratification of being "chosen."

If you are too drunk, look rough or troublesome, you simply don't get invited. That night was a real eye opener.

Last weekend, I returned to this same venue to take a closer, more sober, look.

The partygoers steamed across Capel Street Bridge heading for the after party venue on the northside.

It was so busy, it looked like it was 9pm but was actually 3.15am.

In exactly two hours, the sun would rise over Dublin city.

When we arrived at the venue, the doorman ushered us on to the footpath. The idea was to get the people in as quickly and discreetly as possible through a back entrance of the secret venue which, during the day, serves as a coffee shop/cafe. We entered through a heavy steel door - usually an emergency fire exit down a side street

Walking down the concrete steps, down which deliveries are usually brought to the kitchen, the thump of dance music is audible. It's 'Summer' by Calvin Harris.

This time I hadn't bought a wristband in advance and so I decided to chance my arm with straightforward cash at the door.

There is no need for ID at this venue, as long as you have money and don't sound obvious alarm bells by dress or demeanour, the bouncers are happy to accept cash. I handed over the €10 entrance fee to an Irishman working the door.

Inside, a large crowd were already bopping. Late arrivals handed in their jackets behind the upstairs bar at a cost of €2.

Plumes of cigarette smoke were illuminated by the strobe lights. After years of the smoking ban it is disconcerting.

A large curtain is pulled across the front section of the cafe and the curtain is closely guarded by a bouncer who is the 'gatekeeper' to the outside world. Walking down the stairs, the DJ is ramping up the crowd with high octane techno.

A small bar is located through a doorway next to the steps to the bathroom. I asked the young man serving what drinks they had because there were no beer taps or optics for spirits - nor indeed shelves of soft drinks and bottled beers - visible. "Beer, vodka, whiskey. What do you want?"

Handing in a €20 note for two vodkas, I get €10 in change. The barman goes through a door and emerges seconds later with the drinks.

They are not the dearest drinks I've ever bought and cheaper than the pubs and clubs in Temple Bar - though, of course, they have all the expense of paying their taxes, buying their late night licences, getting fire safety certificates and HSE certification.

The "black market" clubs have none of those overheads and with the after party venues holding perhaps 200 people, money is being made.

Within minutes I was asked if I wanted to buy 'some pills'.

The young man who was a non-national said that I would have to follow him over to the area near the DJ.

"An 'E' will cost €10 and if it's harder stuff then wait here," he said. I declined and headed for the bathroom. Another clubber had opted for the 'harder stuff.' He snorted a white substance off the toilet lid. A young women close by bit a 'pill' in half and passed the other half to a friend.

Washed down with a beer, it certainly was going to make their night last longer.

As I made my way through the crowd to get back to the stairs, I locked eyes with a few familiar faces. These are people that are not the classic 'clubber' and probably not the pill popping type either - lawyers, media, new age business and creative types.

The age profile was early 20s to late 30s. The atmosphere is good and non-threatening. These are the people who just don't want to go home at 3am and want to pull an "all-nighter."

Upstairs there is a chill-out area where the decibel level is a lot lower. It's a hub of chat and drinks, perhaps this is the area for the not-so-hardcore revellers. Three weeks previously I had approached the exit to leave around 4am. A bouncer taking cash from those coming into the club shouted at me.

"Where the f*** do you think you're going with everyone coming up the stairs? Go back, you can't go out now," he bellowed. One narrow door in and the same narrow door out. The safety implications in the event of trouble, or God forbid a fire, were clear.

On the second occasion I visited I left around 5.25am. This time the bouncer unlocked a door and allowed me out the front entrance - but only after a colleague had checked that the coast was clear.

A taxi pulled up and I got in. I asked him about the after party scene as he knew it.

There are half a dozen separate venues on both sides of the river, he said.

The next day I went back to the venue - now serving coffee, pastries, soup and sandwiches and all-day brunches. I asked the restaurant manager if they had found a black jacket at the party the previous night. He led me downstairs to the area which, just hours before, had been hopping with revellers.

Checking through several jackets left behind he smiled: "You'd be surprised what we find in here after our parties."

Sunday Independent