Point taken. I think it is the way things are going. But, it is not illegal to fit remoulds which are Q rated to 80mph. Admittedly, some of the later remoulds and retreads are rated to higher speeds and even their original rating. It is not illegal to fit these tyres. The 156 winter tyres are a different size and rating I'm sure.
It is possible lower speed rated tyres could cause problems, but as they are offered for sale in this country, I think it could make an interesting legal case.
Certainly, if it were to happen to me, I'd take the view point that it was up to the insurance company/police to proove the tyres were not up to the job. They would have to demonstrate it was grip which was the issue, not carcass failure etc through heat. A real can of worms, and one whereby the 50K legal indemnity could be quickly eaten up though.
Would it not be more sensible to suggest that fitting crud like 'Jing Tong Tyre Limited Company' (China) instead to Michelin would more likely case problems. But when did the law make sense? And of course, it is cheaper for insurance companies to refuse pay out on an easily identifiable spec change.
BTW, I believe it is being considered for law that low emissions cars which have special low rolling resistance tyres must be fitted with these same replacement tyres to emsure they remain in tax banding.