Anyone who caught last night's BBC drama, The Child in Time, about a couple whose daughter goes missing while out shopping, will have found it a gruelling watch. As Sam Wollaston in the Guardian wrote: "a deeply affecting portrait of loss and what that does to love, painful but not entirely without hope". I was lucky enough to be on set for a couple of days during the filming back in April. After three or four takes of this scene between Benedict Cumberbatch and Kelly Macdonald as the husband and wife, I tentatively asked the director if I could have one more run through for stills - the emotion was so raw and so intense that I actually felt guilty taking the pictures, as it felt like a terrible intrusion, perhaps one of the reasons I would never make a good photojournalist. Getting to watch actors this good, this close, is a rare privilege.