Lynda Bird Johnson Robb’s predessor as the oldest living child of a U.S. President was an ambassador to which county?
Belgium
Lynda Bird Johnson Robb
Lynda Bird Johnson Robb (born March 19, 1944) is an American chairwoman and magazine editor who served as First Lady of Virginia from 1982 to 1986, before that as Second Lady of Virginia from 1978 to 1982.
 She is the elder of the two daughters of former United States President Lyndon Baines Johnson and former First Lady Lady Bird Johnson.
 She is the oldest living child of a U.S. President following the death of John Eisenhower on December 21, 2013.
John Eisenhower
John Sheldon Doud Eisenhower (August 3, 1922 – December 21, 2013) was a United States Army officer and military historian.
 As a son of President Dwight D. Eisenhower, he ended his military career as a decorated brigadier-general.
 In the administration of President Richard Nixon (his father’s vice-president), he served as United States Ambassador to Belgium.
Lady Bird Johnson Environmental Award
The Lady Bird Johnson Environmental Award is awarded to a U.S. citizen, corporation or non-profit organization whose work demonstrates his or her dedication, passion for and commitment to the environment.
 The award is named for Lady Bird Johnson, former First Lady and wife of 36th President Lyndon Baines Johnson and was established in 1992 by the LBJ Foundation Board of Directors.
 It honors exceptional achievement in the preservation, restoration, or improvement of the natural world that embraces Johnson's style, energy, and commitment to her work.
 The Lady Bird Johnson Environmental Award is in the amount of $25,000. Clifford Hansen
Clifford Peter Hansen (October 16, 1912October 20, 2009) was an American politician from the state of Wyoming.
 A Republican, he served as the 26th Governor of Wyoming (January 7, 1963 – January 2, 1967) and subsequently as a United States Senator (January 3, 1967 – December 31, 1978).
 Earlier, he was the president of the board of trustees of his "alma mater", the University of Wyoming at Laramie in Albany County, then the state's only four-year institution of higher learning.
 He was also a county commissioner in Jackson, the seat of Teton County in far northwestern Wyoming.
 Before his death on October 20, 2009, he was the oldest living former U.S. Senator as well as the third oldest living former U.S. Governor. Maria Redaelli
Maria Angela Redaelli (3 April 1899 2 April 2013) was an Italian supercentenarian.
 At the time of her death, just one day shy of her 114th birthday, she was the oldest living person in Italy, the oldest living person in Europe and the fourth oldest living person in the world (behind Jiroemon Kimura, Misao Okawa, and Gertrude Weaver). Martin Luther King III
Martin Luther King III (born October 23, 1957) is an American human rights advocate and community activist.
 He is the oldest son and oldest living child of civil rights leaders Martin Luther King Jr. and Coretta Scott King. Jeralean Talley
Jeralean Talley (née Kurtz; May 23, 1899 – June 17, 2015) was an American supercentenarian who was, at the age of 116 years, 25 days, the world's verified oldest living person.
 She was previously thought to be the oldest living American, from the death of Elsie Thompson on March 21, 2013 until Gertrude Weaver was verified to be older in July 2014.
 Upon Weaver's death on April 6, 2015, Talley was recognized as the oldest living person in the world.
 Talley received letters from U.S. President Barack Obama on her 114th and 116th birthdays acknowledging her status. Zephyr Wright
Zephyr Wright was a cook for Lyndon Johnson and Lady Bird Johnson from 1942 until 1969.
 When she moved with them to Washington, D.C., several hotels in the Southern United States refused to let her stay because she was black.
 When Lyndon Johnson was Senator, Wright refused to drive to Austin, Texas, with him, telling him, "When Sammy and I drive to Texas and I have to go to the bathroom, like Lady Bird or the girls, I am not allowed to go to the bathroom.
 I have to find a bush and squat.
 When it comes time to eat, we can't go into restaurants.
 We have to eat out of a brown bag.
 And at night, Sammy sleeps in the front of the car with the steering wheel around his neck, while I sleep in the back.
 We are not going to do it again."
 When Johnson became Vice President, he sought Wright's opinion on matters such as the March on Washington for Jobs and Freedom.
 She later witnessed him signing the Civil Rights Act of 1964, and at the signing ceremony, he gave her the pen he had used to sign the Act, saying, "You deserve this more than anyone else." Michael Reagan
Michael Edward Reagan (born John Flaugher; March 18, 1945) is an American political commentator, Republican strategist, former radio talk show host, and author.
 He is the adopted son of former U.S. President Ronald Reagan and his first wife, Jane Wyman.
 He is the oldest living child of the late U.S. President. Luci Baines Johnson
Luci Baines Johnson (born July 2, 1947) is an American businesswoman and philanthropist.
 She is the younger daughter of U.S. President Lyndon B. Johnson and his wife, former First Lady Lady Bird Johnson.