Much like her late mother-in-law Princess Diana, the Duchess of Cambridge loves a smart, tailored coat by Catherine Walker. Kate Middleton has worn the designer for countless public engagements, ever since her very first royal tour with Prince William in 2011. But of all the gorgeous outerwear she has worn by the designer, there is one piece that Kate seems to love the most — the cerulean blue Catherine Walker coat. For Kate's latest outing with the blue coat, the Duke and Duchess of Cambridge arrived in Scotland for the first day of their Royal Train Tour. The Duchess paired her sleek coat with black leather gloves, a black Strathberry Multrees Chain Wallet clutch, and black suede Ralph Lauren Collection boots. The first time we saw Kate in the Catherine Walker coat was in 2018 for the Cambridges' Norway tour when she was expecting Prince Louis.