Springwatch was originally launched as a rival for BB, it used to be on at the same time to compete and so he used to make jokes during the show about our wildlife live and interactive against humans live

that was when Channel4 was getting massive ratings in the first years.
He took time out of Springwatch due to a very bad depression he was suffering. When he was much better a few years later, they had him on as a guest. But he said that they would not offer him a presenter job back
I think Big Brother would have been really wrong for him and he might not have passed the psych tests, some other celebs are rumoured to have been rejected! he is very entertaining though but glad he turned it down. I felt very uncomfortable seeing Paula Hamilton there last year