Positive should always be brown and negative always blue, zbungle, regardless of whether you are in the UK or on the Continent, zbungle. The main difference is that, in general, most relatively low current electrical equipment on the Continent is not earthed (in fact their plugs are reversible), so it's immaterial which way round it is connected. Because of this, the Continental caravanner doesn't have to take care to watch for correct polarity.