Mayor of London Boris Johnson called on Irish people to help make this summer's Games the "O'Lympics" as he took part in St Patrick's Day festivities.

He joined thousands of revellers, including Irish Olympians and Paralympians, for the annual parade of colourful floats. It ended in a festival of music, dance, crafts and food at Trafalgar Square.

Describing the turn-out as "fantastic", Mr Johnson said: "I think it shows the amazing strength of the Irish community in London. We must have tens of thousands of people here today.

"There is an enormously optimistic mood and I hope that some of the spirit we have got here from the Irish community will feed on through to the summer where we are putting on the greatest party, the greatest show on earth.

"Let's hope that we put the apostrophe into the O'Lympics."

He praised the "real skill of the Irish community in educating everybody in the business of having a party" but admitted "there are anxieties about some aspects of" the Games.

He went on: "There is anxiety about keeping the costs under control. It's very important that we continue to do that. There is anxiety about transport systems and the security. But I think that most people know in their hearts we're going to put on a fantastic show. It will be a great Games."

He received some boos as he took to the stage to address revellers. He told them: "I know the spirit of the Irish community is going to be at the heart of what we do this summer."

Ireland Olympic Chef de Mission and Olympic silver medallist Sonia O'Sullivan said of the parade: "I have never seen anything like it."

She said Irish people were pleased to have the Olympics so close to home, and added: "A lot of them are really inspired by the Olympics being in London. It's a goal. They really want to get there because it's so close to friends and family."

The Press Association, photo: The CBI