It's not often that the grim European quarter of Brussels rocks. But on Thursday it witnessed its biggest and loudest street party since the Iranian opposition invaded Schuman square several years ago with a sea of flags and four-storey speakers.

The official excuse for the party was the opening of the Czech House, a building that will house the country's embassy to the EU and most of the adolescent republic's businesses and regional groupings in Brussels.

But the real reason for the bash was to announce to all who haven't noticed yet that the Czechs have arrived at the heart of Europe - and arrived in style.

To prove it, they wheeled out chart-topper Iva Fruhlingova - who is way too good-looking to be taken serioulsy as a chanteuse - and eclectic punk-folk band Cechomor all dolled up in traditional dress. There were also street stalls serving up sausages, fruit-filled dumpings and Becherovka, advertising Czech Airlines and Plisner Urquell and showing off the attractions of Karlovy Vary and southern Bohemia. In fact the only thing mising was beer - a crime at a Czech party - which had all been guzzled by the time I got there.

An English friend once told me that she was afraid of the EU's enlargement to the east because it would bring in a swathe of leggy beauties who would make western European women look plain in comparison. How right she was. The Czech street party was more like a models' convention than an office opening. Even the coat-ladies looked like they's walked out of a Victoria's Secret shoot.

My English friend was not the only one who feared the entry of the Czech Republic and the other nine former communist countries who joined the EU in 2004 and 2007. Many EU officials and several European leaders - most notably former French President Jacques Chirac - were petrified that the new arrivals would glue up the EU's decision-making machinery, flout the club's rigorous rules and dilute the European 'project' with their uncouth manners and Atlanticist bonds.

They have been wrong on every count. The eastern enlargement of the EU has been wholly beneficial to the 27-member club. It has brought in skilled workers to do the jobs westerners are either unable or unwilling to do. It has opened up unpronouncable areas of eastern Europe to cheap flights and holiday homes. It has hardened the EU's kid-glove approach to Russia and softened its abrasive stance towards the United States. And it has not prevented major decisions being taken on the constitution, the budget and Turkish membership of the EU.

But most importantly, enlargement has brought a breathe of fresh air to Brussels and the drab EU quarter many people associate with the Belgian capital. By the end of Thursday night the air was spiced with more than a hint of sausages, smoke and beer - but it smelled all the better for it.