A variation of Heisenberg's uncertainty principle would almost undoubtedly apply. If you have a different system the results will not be the same.
Given the FPTP squeeze on Lib Dem votes in the large majority of constituencies, a higher final Lib Dem vote that 11.5% would be more likely than a lower one.
Probably true though the lib dem vote overall may well be more spread out than it is now. Places where the lib dems squeezed other parties (St Albans, Esher and Walton) could well see a decrease in those places under PR.
A conservative who has always lived in labour areas.