St Patrick's Day celebrations kick off

Dressed in green and armed with pints of Guinness, revellers didn't waste time in celebrating St Patrick's Day in Sydney.

Before midday on Tuesday, Irish dancers were already tapping away on the floors of a Sydney CBD pub, accompanied by a jigging band and the cheers and claps of onlookers.

Amid the growing bustle, PJ O'Brien's general manager Fergal McCauley was behind the bar, pulling pints and preparing himself for their busiest day of the year.

"Today is traditionally the biggest day without a doubt," he said, adding they opened the doors at 8am to start serving Irish breakfasts to about 400 patrons.

Then it's onto lunch, again for around 400-500 meals over two windows, before kicking on into the night and finally closing up at 2am.

"So just a small 18-hour day," Mr McCauley laughed.

As an expat himself, Mr McCauley says St Patrick's Day means a lot.

"It's always a big day for celebration, everyone goes out and dresses in green. It's all about music, song, dance," he said.

"Me being from Ireland, it's nice to be somewhere traditional on the day, celebrate with your friends - everyone that comes here is part of home really.

"Get a pint of Guinness, a beef and Guinness pie, Irish breakfast... Irish traditional music on, Irish dancers, it's a perfect day for everyone who's not at home."

Irish beer plays a big part on the day, with Mr McCauley saying they sell about 15-20 times more Guinness on St Paddy's day than any other day in the year.

"You're looking at about 3500-4000 pints alone which is somewhere between 35-40 kegs of Guinness today," he said.

"Everyone's drinking it today as tradition."