Prince William

Presumably you mean why is Princess Anne after Princes Andrew and Edward in line of succession?

If so, it is because the current Law of Succession states that male issue of a reigning sovereign take precedence over female issue. Thus, Princess Anne, the Princess Royal, was second in line to the throne until 1960 when Prince Andrew was born, relegating her to third. Subsequently, the Queen's youngest child, Prince Edward relegated her to fourth place. Since then, both Princes Charles and Edward have male heirs, relegating Princess Anne still further.

However, in October 2011, at a meeting of the sixteen countries of which Queen Elizabeth II is sovereign, Prime Minister David Cameron proposed a change to the Royal Precedence Act, which received tacit endorsement from the other 15 states. This change, if ratified would instaure the principle of primogeniture, and Anne would take precedence over her younger brothers, although obviously Prince Charles, who is her elder by two years, and his son, William will remain heir and heir apparent. But, in order for this change to take effect, it must be ratified by the Parliaments of all 16 nations of which the Queen is sovereign. Wikipedia states it thus:

"The Commonwealth realms-the United Kingdom, Canada, Australia, New Zealand, Jamaica, Barbados, the Bahamas, Grenada, Papua New Guinea, the Solomon Islands, Tuvalu, Saint Lucia, Saint Vincent and the Grenadines, Belize, Antigua and Barbuda, and Saint Kitts and Nevis-are all equivalent in status, and independent of each other, while sharing one monarch in a constitutionally equal fashion. As such, changes to the succession laws, according to convention, must be identical in and approved by each country, though the procedure varies between realms."

It was reported that, at age seven, the Prince said to his mother that he desired to be a police officer when he was older, so that he might be able to protect her; a statement to which his brother responded: "Oh, no you can't. You've got to be King. William's first public appearance was on 1 March 1991 (Saint David's Day), during an official visit of his parents to Cardiff, Wales. After arriving by aeroplane, the Prince was taken to Llandaff Cathedral, where he signed the visitors' book, thereby demonstrating that he was left-handed. On 3 June 1991, William was admitted to Royal Berkshire Hospital after having been hit on the side of the forehead by a fellow student wielding a golf club. The Prince did not lose consciousness, but did suffer a depressed fracture of the skull and was operated on at the Great Ormond Street Hospital, resulting in a permanent scar. William's mother desired that he, along with his younger brother, not just have "normal" experiences that other royal children had not had until later in life, if at all, but also more profound lessons, taking both boys to locales that ranged from Disney World and McDonald's to AIDS clinics and shelters for the homeless. She also bought them things typical teenagers used like video games. Diana, Princess of Wales, who was by then divorced from the Prince of Wales, died in a car accident in 1997. William, along with his brother and father, was staying at Balmoral Castle at the time, and the Prince of Wales waited until early the following morning to tell his sons about their mother's death. At his mother's funeral, William accompanied his father, brother, paternal grandfather, and maternal uncle in walking behind the funeral cortège from Buckingham Palace to Westminster Abbey.Prince William was born at St Mary's Hospital in London, England, on 21 June 1982, the first child of Prince Charles, Prince of Wales, andDiana, Princess of Wales, and third grandchild of Queen Elizabeth II and Prince Philip, Duke of Edinburgh. According to a bet taker at a horse race at Windsor Castle in 2004, "We ran a bet before Prince William was born on what his name would be. About an hour before the announcement, a very large bet came in for 'William', and I've suspected that the wager came from the palace since." Baptised in the Music Room of Buckingham Palace on 4 August 1982 (the 82nd birthday of his paternal great-grandmother, Queen Elizabeth the Queen Mother), by the then Archbishop of Canterbury, Robert Runcie, William's godparents were King Constantine II of Greece; Sir Laurens van der Post; Princess Alexandra, The Honourable Lady Ogilvy; Natalia Grosvenor, Duchess of Westminster; Norton Knatchbull, Baron Brabourne; and Susan Hussey, Baroness Hussey of North Bradley. As a male-line grandchild of the sovereign and son of the Prince of Wales, William was styled His Royal Highness Prince William of Wales, though he was affectionately called Wombat or Wills by his parents.

After graduating from Eton, the Prince took a gap year, during which he took part in British Army training exercises in Belize, and, for ten weeks, taught children in the town of Tortel, in southern Chile, as part of the Raleigh International programme. It was during his time in the latter location that he lived with other young teachers, sharing in the common household chores, including cleaning the toilet, and also volunteered as the guest disk jockey for the local radio station.

By 2001 William was back in the United Kingdom and had enrolled, under the name William Wales, at the University of St Andrews. News of this caused the number of applications to St Andrews to swell, mostly from young women who wanted an opportunity to meet the Prince. The extra attention did not deter him, though, and he embarked on a degree course in art history, later changing his main subject to geography, and going on to earn a Scottish Master of Arts degree with upper second class honours in geography - the highest honours of any heir to the British and other Commonwealth realms' thrones. While at university, Prince William also represented the Scottish national universities water polo team at the Celtic Nations tournament in 2004. He was known as "Steve" by other students to avoid any journalists overhearing to understand.