[AndyK]

There are no longer any frontier controls at the borders between 13 EU countries. This is thanks to the Schengen agreement which is part of EU law. The Schengen rules remove all internal border controls but put in place effective controls at the external borders of the EU and introduce a common visa policy. The full Schengen members are Austria, Belgium, Denmark, Finland, France, Germany, Greece, Italy, Luxembourg, the Netherlands, Portugal, Spain, Sweden (but not Ireland and the United Kingdom) plus Iceland and Norway (which are not EU members).

The 12 countries that have joined the EU since 2004 do not yet fully participate in Schengen. You will therefore need a valid passport or ID card to travel to those countries and to Ireland and the United Kingdom.

So, us Uk'ers need passports.