1917 director Sam Mendes claimed that he cast George Mackay because he wanted an 'unknown' actor as the lead. This is horseshit, because he played a lost boy in Peter Pan (2003)
1917: Watch the first trailer of Sam Mendes film starring Richard Madden, Benedict Cumberbatch
Colin Firth, Benedict Cumberbatch Join Sam Mendes' WWI Movie '1917' – The Hollywood Reporter
1917': Who's In The Upcoming Movie, What's It About, And When Does It Open?