OK, I realise that the below article is likely to hit a raw nerve with some hiring business owners and senior decision makers, but bear with me.  

All too often interviewers leap straight into the Spanish inquisition, testing a candidates focus and abilities under pressure.  

Instead, my advice on first interviews is to trust the judgement of your headhunting partner.  Any recruiter who says they always get the hardened skills required right all the time is simply fibbing, but, assuming you have partnered your headhunter previously, they will have a good handle on what is required from a skills set perspective.

This allows the company to mainly focus their attention around cultural and personality fit for the business at first interview stage.  In turn, this leads to a more human interaction, with the candidate (who if headhunted is unlikely to be actively looking) leaving the interview with a warm fuzzy feeling about you (OK, slightly over egged but you get the picture).  The interviewer will then get the chance to cross-examine during the second interview.