Good, thorough and challenging - conversational not confrontational. Sense of camaraderie amongst fellow staff is reassuring.Only criticism would be that the senior person meant to interview me failed to appear.

Moderately challenging for a senior position, the benefit for me was that I had begun my career in that environment so had most of the requisite knowledge. I would say the more challenging aspect was discussing management style, campaign awareness, skills development you've proactively undertaken which differentiates you from other juniors etc.