Tom Kiely won in 1904, Daley Thompson won in 1980 and again in 1984. So the answer is two, but three times. Thompson is one of two people (American Bob Mathias the other) who have repeated as Olympic Decathlon Champion.
Here is another asterisk to add. In 1980 many countries boycotted the Olympics in Moscow, then in the Soviet Union. Great Britain attended but competed under the Olympic flag in support of the political issues for the boycott.
Twice ... Bob Mathias of the United States at the 1948 Games in London and 1952 Games in Helsinki and Daley Thompson of Great Britain at the 1980 Games in Moscow and 1984 Games in Los Angeles.
Once ... Cornelieus Leahy won gold in the high jump for Great Britain at the 1906 Olympics.
3 times
3 times
Lots
Once, at the 1936 Games in Garmisch-Partenkirchen.
Bruce Jenner was a decathlete and won the gold medal in decathlon at the 1976 Summer Olympics in Montreal.
Great Britain was explored in prehistoric times. No records remain of who did it or of precisely when.
King William I Was a Ruler Of great Britain in The Medieval Times. King William I Was a Ruler Of great Britain in The Medieval Times.
Bruce Jenner won the gold medal in the decathlon at the 1976 Montreal Olympics with a total score of 8,634 points. His individual event times included a 100 meters time of 10.93 seconds, a 400 meters time of 47.51 seconds, and a 1500 meters time of 4:12.51. Jenner's performance in various other events contributed to his overall score, solidifying his status as a top athlete in the decathlon.
Once as England, the first time field hockey was in the Olympics, and twice as part of the Great Britain team. All were victories by the men's team; the closest the women's team has come was bronze at Barcelona 1992 (as part of Great Britain).
three times