I've never had any issues with UK registered cars in CH or anywhere else and I know I have been flashed on the motorways and received parking tickets on various occasions over a 4 year period.
However driving to the UK a few weeks ago in our Swiss registered car I did get a speeding ticket just south of Reims. 60 Euros.
I understand it's now normal practise that all neighbouring countries in europe cooperate with each other for motoring offences.

Good luck, you never know, you may have got away with it! but don't ignore it if you do get a fine.

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"Orbis non sufficit"