By Joseph Wilkes & Rebecca Russell Kate Middleton is “especially grateful” for a “discreet” royal friend who is “worth her weight on gold”, as the Princess of Wales continues her recovery from cancer, according to a royal expert. Royal insiders have revealed Kate’s closest friends and trusted aides have rallied round her, creating a tight-knit support system as she gears up for a return to Royal duties. Kate has stepped back from the public eye to focus on her health and has been leaning on her trusted inner circle amid her cancer treatment while finding solace away from her Windsor family hom…