The Bafta-winning director-writer has announced that he will write one of the episodes on the award-winning sci-fi drama, featuring the new Doctor, Matt Smith.
"It's tremendously good fun and a treat for my children - These days, the things you can watch together as a family are much fewer so when you get something like Doctor Who or The X Factor, it is such a pleasure to sit down as a family," Richard told The Sun.
But Richard - whose works include Notting Hill, Love Actually and Four Weddings And A Funeral - is staying schtum about the plot.
"There will be a monster. And a famous historical figure will battle the monster," he said.
"I am very interested in time travel for some reason or other. Maybe it's a desire to get out of being old. Sometimes you do just love the idea that you could go back in time and change things."
The fifth series of Doctor Who, to air next year, started filming around six weeks ago and will see Alex Kingston returning as Professor River Song.