Vickers has written many royal biographies, including ones of Queen Elizabeth The Queen Mother, Princess Alice of Greece and Denmark—which was approved by her son, Prince Philip, Duke of Edinburgh—and Gladys Spencer-Churchill, Duchess of Marlborough. Over the course of his career, he has regularly participated in royal occasions, being a studio guest for both the wedding of Charles, Prince of Wales, and Lady Diana Spencer in 1981 and Diana's funeral in 1997. Moreover, he commentated on ITN with John Suchet in 1999 for the wedding of Prince Edward, Earl of Wessex, and Sophie Rhys-Jones, for the Queen Mother's centenary celebrations in 2000, and for her funeral two years later. He frequently appeared on CNN's former programme, "Larry King Live", and has also appeared on Fox News Channel, MSNBC, and television programmes in Canada, Australia and New Zealand.