This slide is marked 'Snetterton' with Norton Manx shown, undated.

Now Snetterton does have structures around the track,  but this looks weird perhaps due to perspective?
 can't tell if that's pavement in back with a stonewall and structure?  Or if that's pavement and verge and a barrel or vent behind?
Or just an artifact of the camera behind the rider?
To add to the confusion I've been told the slide is mis-labeled and that this was taken at the IOM...
comments?   regards

Looks like an airfield circuit to me, so Snetterton would be my guess.

Yes on second thought, looking closely that's apparently the verge and then horizon in background, with a signpost just being passed by the rider, which is consistent with Snetterton.