An emotional documentary on Princess Diana has hit UK TV screens, with Princes William and Harry giving their most candid interviews to date.

The documentary, Diana, Our Mother: Her Life and Legacy, airs in New Zealand tonight

Royal commentator Phil Dampier told Mike Hosking Prince Harry was seemingly numbed by his mother's death.

"Harry said in an interview earlier this year that for many, many years, he probably suppressed a lot of the feelings that he felt about his mother's death, and admits in this programme that he's only ever cried twice."

Dampier said Prince Charles is conspicuously absent from the new documentary.

"A lot of people are saying that Prince Charles must feel rather upset by this programme ... [there's] very little reference to him."

LISTEN ABOVE AS PHIL DAMPIER SPEAKS WITH MIKE HOSKING