A second round of celebrations marking Queen Elizabeth II's 80th birthday begins Thursday, Buckingham Palace said. About 40 members of the royal family -- including the queen's husband, Prince Philip, her heir, Prince Charles, and his sons, princes William and Harry -- will be among the 2,300 people at the venue of the festivities. British Prime Minister Tony Blair is also on the guest list, as are former Prime Ministers Margaret Thatcher and John Major, the Associated Press reported.