How to handle a difficult (stroppy) person

I watched Alan Stevens, the Media Coach, handle a stroppy person last week at an intimate dinner meeting in the House of Commons with an MP I mentor. He used a technique that I call a mixture of the "Columbo Close combined with Pattern Interupt". Columbo from the TV programme - I must be a bit thick, run it past me again and a pattern interupt (from cognitive behavioural therapy CBT) to throw the stroppy person.

Alan was in the course of answering another guests question, when "SB" lets call him interupted to disagree. He did this three times, on the third time with Alan's patience, and the others guests patience, running out, Alan just said sorry I don't understand your question and I have also totally lost the thread of what I was saying.

He got an apology, but refused to go back to the point he was making. This stopped SB in his tracks. We were all slightly embarrassed, some people felt sorry for Alan, some people were admiring his skill.