It would be the 28th and last time the world final would be held in England under the traditional single meeting format.
Jonsson defeated Shawn Moran from the United States in a run-off after both finished the meeting on 13 points.
Moran was later stripped of his second place by the FIM for failing a drug test taken at the Overseas Final.
Australian youngster Todd Wiltshire, believed by many judges to be one who would be making up the numbers in his first World Final, finished third with 12 points after winning his first two rides.
Defending champion Hans Nielsen, the only Dane in the field following an injury to Jan O. Pedersen which kept him from riding, finished in 4th place with 11 points.