According to BBC’s Doctor Who website, “David Tennant's Tenth Doctor is set to meet Peter Davison's Fifth Doctor in a special scene commissioned for BBC One's Children in Need. The scene, entitled Time Crash, was written by award winning Doctor Who writer Steven Moffat, and will transmit as part of the Children in Need fundraising evening on Friday 16 November 2007.”
Peter Davison said, "It is an honor for me to be able to make the connection between the Fifth Doctor and the Tenth Doctor, however… I can feel the hand of history on my shoulder.” Looking at the promo picture on the BBC website we are reminded that Davison has not played the Doctor since 1984. He is now 56 years old but when he took the role as the Doctor in 1981 he was the youngest actor to have ever played the part at 29.
I am glad they are doing this television short for the Children in Need charity. I think this is a great medium to have a short fun story about the fifth and tenth Doctor meeting rather than trying to do something like this in a regular episode.