Tom Baker detested the character of K9, but got on very well with Leeson. A favourite joke during filming breaks was for Baker to work out crossword puzzles, asking the K9 prop the clues with Leeson giving the answers in character. The short sketch Merry Christmas Doctor Who involved K9 telling the Fourth Doctor and Romana I that for Christmas he would like "enough ball bearings to last the series through and fewer sill irons on the floors of the planets we visit," as well as the robot dog downing some gin before beginning a drunken rendition of "We Wish You a Merry Christmas". When Leeson appeared on Tom Baker's edition of This Is Your Life in 2000, Leeson entered on all fours.