Britain's Prince William, Duke of Cambridge (R), and his wife, Catherine, Duchess of Cambridge arrive to attend a Guild of Health Writers conference in London on February 6, 2017, this year focusing on mental health, and supported by the Heads Together campaign.

a big Assembly at a primary school in London to mark Children's Mental Health Week on February 6, 2017.  / AFP / POOL / Eddie MULHOLLAND        (Photo credit should read EDDIE MULHOLLAND/AFP/Getty Images)