Quote Originally Posted by the leader View Post
You're wrong. It is people with holiday visas who are most likely to be stopped by customs and interviewed. They are easier to spot if their intention is not to go back.
Actually they have interview centres in the host countries, run by or on behalf of the British Embassies. Any person who fails to meet the stringent requirements will be refused a visa, which could be the vast majority of applicants depending on the country in question, so they will never even get as far as Heathrow.