It was explained on this forum once that the promoter at the time wasn't an astute businessman, although he loved his speedway. It was alleged that he never applied to extend the planning permission beyond the 1987 season and once it had lapsed, Canterbury Council declined to renew it.
And is the site now too near a built up area to be revitalised? it looks as if the layout is still intact but it's difficult to see what there is around it.
Kingsmead is only a mile or so from the City centre and is located in a built up area, however, at a guess, 50% is industrial or retail usage. I'm sure with the advances over the years in noise reduction, the return of speedway wouldn't be a real problem for local residents but what their reaction, or the councils for that matter, may be I've no idea.
The supporter base is definately there and any prospective promoter who could obtain the relevant permission, would I'm sure, be rewarded with extremely good attendance levels. However, as you have seen from the photos, a stadium would have to be built from scratch and therefore would involve a fairly high investment.
I have a dream that one day the roar of Speedway bikes will return to Canterbury and there have been a few rumours over the years but no real actions. Anyone with a few thousand pounds to spare could do far worse than look at re-introducing Speedway to Canterbury.