Depends Bigmartin where you draw the line between left and right!
To some Tommy Robinson is a wishy washy liberal and to others Corbyn was really a conservative, it’s all about individual perception.
You are correct when you state your a,b.c examples are certainly in my perception more right than left of centre but in the main with the exception of Thatcher they are all just middle left or just middle right and they have been in power because that is exactly what the population want.
They don’t want "far" anything just moderation.
There are many who support Momentum, there are many who support EDL but the vast majority reject both sides in favour of moderation.
And IMO that’s how it was, is and will probably always be.
When I see the hate, yes hate and rants expressed by both sides of the political balance it sickens me and just pushes me further to the middle ground as I believe is the case with many others.