The point I made in my post explained all this, but to requote myself - The "silent Majority" are generally centralists...[snip]
We have had the exact same situation here - the "silent majority" voted Tory when no-one predicted they would, and when they did they caused a landslide.
Well, that's not true for a start, it was the Labour base voting Tory (due to Brexit) when they never had before that caused the "landslide" result, not the middle swing voters, who by definition vote one way or the other anyway.
To be an equivalent to the US it would be the Democrat base all of a sudden coming out and supporting Trump and that's not likely to happen is it.