It is the first time that the trio have appeared at a royal engagement together without the Duchess of Cornwall.
Kate wrapped her growing baby bump from the unseasonably bitter chill in a red angora wool coat by Armani.
The duchess, famous for 'recycling' her outfits, wore the same luxurious coat for William's passing out ceremony at Sandhurst in December 2006.
The formidable fashionista continued Thursday's tartan wardrobe theme by wearing a Strathearn tartan scarf, a nod to her Scottish title, the Countess of Strathearn.
She teamed the colourful accessory with her trademark black opaque tights, her beloved Cornelia James bow gloves, long suede boots and a matching clutch bag. Click link for full post from Hello Magazine.