Popsugar Parenting The Royals Prince Louis Sucking His Thumb At Trooping the Colour 2019 The Duchess of Cambridge Smoothly Stopped Prince Louis From Sucking His Thumb During a Royal Event 9 June 2019 by Karenna Meredith First Published: 8 June 2019 View On One Page Photo 1 of 11 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 1 Previous Next Start Slideshow The RoyalsBritish RoyalsPrince LouisKate Middleton