In Part 1 of the Downton photo diary, the Irish actor explains why he and Hugh Bonneville (Lord Grantham) posed with a crew member hiding under a table; why he himself had to “have a lie down” on the ground (the same reason Laura Carmichael, who plays Lady Edith, sat on him); how the dog who portrayed Isis came to be wearing a top hat; what he did to earn the nickname “Magic Man” from the show’s child actors; and what moved him to dance with Elizabeth McGovern (Lady Grantham) between takes.