Charles is dressed in a lacy white outfit, and is lifted out of the pram by a doting Philip, who then sits him on his lap.
Knelt down on a blanket laid out on the grass, Queen Elizabeth sits with a teddy bear looking on lovingly as Charles plays with his toy.
The baby then gives a couple of adorable sneezes, making the Queen chuckle.
The final clip shows Charles pulling on her elegant pearl necklace while she holds him and laughs adoringly.
More never-before-seen is due to be released in ITV's documentary Queen of the World, airing on Channel Seven on October 1.