These programmes are obviously fully researched before the subject is filmed, and are presented in a slightly artificial way. This week's programme seemed to be more artificial than most.
I think this is unavoidable. Think about it, if you were a celebrity and you were approached by a TV film company, wanting to research your ancestors and broadcast the results to the nation, I'm pretty sure that you would insist on seeing what they had found before it was broadcast. Apparently Patsy Kensit wanted to pull out of the show when another of her ancestors was found to have a shady past, but she was persuaded to carry on with it.
The alternative would be to just present the person's ancestral file, without any involvement with the celebrity themselves, and although I'm sure that whilst most Roots Chatters would find that fascinating, the rest of the population would find it as riveting as watching paint dry. So, what has to happen is that the celebs take part, and they do know in advance most of what's going to happen, and they look surprised for effect.
It's still a good show, despite its shortcomings
