I saw a posting on the internet, he had been taken into hospital suffering from pneumonia. Another posting mentioned that the producers were looking for someone to stand in for him, they were expecting him to be 'out of action' for quite a long time. I wondered if the producers were showing 'old' programmes, or if he is back, fit and well. Hope so, seems like a nice bloke.
Everything up to the end of the current series was recorded a couple of months ago, before he went into hospital. He'll be back, but it takes a while to recover from pneumonia, so there will be guest presenters for the first few weeks of the next series, which begins next month.