Bingo, exactly right answer.
Smoke in the distance is a clue if you're a local. Manston Airport, where there is a Fire Service training school.
Here's the view looking S a few minutes earlier. The tower is actually Reculver Towers, looking side on.
The boat ain't me, by the way, but perhaps someone knows who he is....
It's got to be Kent; no other config fits. That gives us the choice that the mark is Spile. Columbine or Hook Spit. Don't think its Columbine. Spile then with Leysdown in the background.