"....protest vote from the conventional Tory voters either to Labour – in great numbers – and to some extent fringe parties like Reform UK ...."

I may be wrong, but as I watched a few of the results coming in it looked like ... Or I assumed from basic back of envelope calc ... That most reform votes poss 75% came from ex Tory's as their numbers plus and minus seemed to balance ( with a smaller percentage to labour . Poss say 25%)

I haven't checked since.
And hadn't factored in the idea ( evidence?) that Tories had stayed at home.