On the blog amcherryfairy, this mother describes how Peter Capaldi went out of his way to talk to a her autistic daughter about Matt Smith's departure from the show. The family just happened to be vacationing in Cardiff and ran into the Series 8 shoot. Apparently-
"when matt smith said he was leaving she was worried, because she goes on adventures with doctor who and Clara and she was worried that the new doctor ( Peter ) would not like her and wouldn't want to join in her games.".During their visit, the family met Jenna Coleman and Samuel Anderson, who told them to come back the following day to meet the Doctor himself, Peter Capaldi.
Jack Robinson is 4 years old, a huge Doctor Who fan, and has an inoperable brain tumor. No one knows how Matt Smith heard about the little Whovian, but according to Jack's dad, he loved the video. "His eyes just lit up and he was so delighted. It has made his day."