Congratulations to Stig. That is indeed the longest breath-hold I have ever heard of.
However, even though I have rarely seen it referenced, John Mithoefer wrote the following in 1965:
“As inspired oxygen tension increases or initial carbon dioxide tension is lowered by hyperventilation, breath-holding time becomes progressively prolonged up to the astonishing length of 20 minutes and 5 seconds after 7 minutes of hyperventilation with air followed by several deep breaths of oxygen. This feat is said to have been accomplished at Wesleyan University by a student named E. Frechette, a cross-country runner who was in peak physical training at the time of the breath hold; he is said to have had an unusually large vital capacity in relation to his body size.”
(Citation from “Mithoefer, J.C. (1965). The breaking point of breath holding. In: Rahn, H., and Yokoyama, T. (eds.) Physiology of breath-hold diving and the Ama of Japan. Publication no. 1341. National Academy of Sciences, National Research Council, Washington, DC., p. 195-205.”)
In his text, Mithoefer refers to personal communications with someone called R.A. Gortner at the Dept. of Biology at Wesleyan University. Obviously, I cannot guarantee that the statement is correct, but if true, the 20 min limit was broken more than 45 years ago. But I guess that will be difficult to verify...