By Ellie Fry Princess Kate had a deeply personal motive for delivering her cancer message alone, a royal expert has revealed. The Princess of Wales’ brave video left royal watchers around the world in tears on Friday, as she shared she is currently undergoing preventative chemotherapy for cancer. Dressed informally in a striped jumper and jeans, perched on a dark brown bench on the backdrop of beautiful spring daffodils, Kate told of her “complete shock” after doctors found cancer was present during post-operative tests following major abdominal surgery. Visibly emotional, the future Queen sai…