Baby Prince William joins 'The Crown' season 4

Cape Town – The Crown has just added its cutest co-star.

Filming of season four of the upcoming royal Netflix drama is currently underway.

New cast spotted on the set include Gillian Anderson as Margaret Thatcher and Emma Corrin as Princess Diana.

READ MORE: Emma Corrin is Princess Diana's lookalike on set of 'The Crown'

But the newest cast member spotted will make everyone go 'Aww'.

On Thursday the cast was pictured filming Prince Charles and Princess Diana's 1983 royal tour of Australia in Spain. The couple were joined on tour with their 9-month-old son Prince William, reports ET Canada.

In the pictures obtained by the publication, the cast can be seen carrying a baby Prince William onto the plane.

SEE THE PICTURE HERE:

According to Town and Country Magazine, this was the first time Diana travelled overseas and it was also William's first tour as she reportedly refused to leave him at home with caregivers.

Prince William, Princess Diana and Prince Charles

(1983: Prince Charles, Prince of Wales and Diana, Princess of Wales visit Australia with their son, Prince William. Photo by Tim Graham Photo Library via Getty Images)

The fourth season of the drama will take place roughly between 1979 to 1990 and will focus primarily on Princess Diana and Margaret Thatcher, reports The Hollywood Reporter. 

Prince Harry might also make an appearance as he was born in 1984.

Season 1-3 is available to binge on Netflix.

Compiled by Leandra Engelbrecht (Sources: ET Canada, Town and Country Magazine, The Hollywood Reporter).

(Photo: Getty Images)