Trengwainton, August 1966
Stopping distance at the top became an issue (unjustifiably so and down to one individual's influential opinion according to a regional champion who competed there in the 70s). Then overtaken by National Trust taking it over (same NT problem as Dyrham Park).
Regarding Dunkeswell, the earlier comment regarding Kirstie Allsop should be re-directed at Nigel Mansell. I'm sure that has been covered before here but the problems with Dunkeswell were Mansell's development plans, not the existing use for karting and car sprints. Even then, IIRC, he could have secured his planning assents if he had been willing to compromise on the height of one building. Instead he seems to have gone off in a huff and left the place blighted for sprints.
Thorney Island was used for stage rallying in the 80s.
Edzell was due to be used for stage rallying (after the USN puilled out?) in comparatively recent years.
Clay Pigeon kart track was used for a car sprint for the first time this spring and another is scheduled for October. Like most new speed venues, low entries initially - and that may kill it.
Some of the venues being mentioned (Zig Zag Hill nr Blandford?) were public road hill climbs that were run all over the place up until the Kop Hill problem (1920something?). Chris Mason's "Uphill Racers" lists many of them but it will be a long list if repeated here.