Interview technique

Earlier today I was interviewing this guy for a web development role and wondering whether or not I should tell him that he was flying low before palming him off on one of the juniors for an office tour. He'd blown the interview anyway, he actually showed real passion while explaining how he'd use UML diagrams to design a simple bookshop website. There's no place on this ship for a coder who can't think in Assembler. Then he tried to persuade me that all our problems would be solved if we just adopted PRINCE2. This guy's got four year's experience at a big consultancy firm and I was beginning to wonder if he'd ever actually written a line of source code or checked anything in to source control other than diagrams, specs and project management documents.

So I pulled a recursive Perl problem from the stack of interview questions, that one really sorts the men from the boys. It's a handy little problem that gives me the ammunition I need to get the personnel department to send off the standard thanks but no thanks missive, and the candidate the fervent wish to work elsewhere.