I never really believed the women in the UK dressed or acted differently to the women from the rest of Europe ... until I studied abroad, the predominant drunken behavior and small amounts of clothing, does appear to be a common trait of the British and Irish female.
Why? I don't really know, however I do not believe they are anymore promiscuous than their continental cousins, immature, yes. Willing to drink themselves into oblivion, yes (though closely matched by the Finish girls there) Show a lot more flesh, yes, but in my estimates no 'easier' or 'harder' to 'pull'.