I am not sure you are getting the point. Just considering England, it used to be that there were two parties on "the left" and one on the right. This disadvantaged the left, but they have sort of built voting blocks that are not too antagonistic to each other and so has managed to gain a modicum of power on occasions.
The "right" has never had to do this, and while being riven with ideological divisions has managed to maintain a coherent voting block and so managed to wield more power than anyone else for hundreds of years while never having any sort of majority support.
They are now faced with a changed landscape, where the fascists have their own party that MAY be unpalatable to the "one nation" wing of the tory party. They are really not set up to compete in a landscape where their vote is spilt between the racists and the economic right wing. This is not unique to the UK, but FPTP makes it particularly dangerous for the tories.
There is a certain irony that Brexit was largely an attempted to maintain this voting block, but may have ended up cementing its division.