we don't know because our inflation was then (Back Wednesday, 16-Sept-1992) HIGH compared to Germany, France Benelux etc that the Pound could not be kept within the 'snake' that was the ERM.Remember those Remainers are the very same people who thought us joining the Euro would be a good idea! (Imagine the disaster that would have been!)
Notice that we have had higher inflation than in the Eurozone ever since its inception.
Had we joined, inflation and mortgage rate would have been much lower.
Remember high inflation hurt the poor much more than the rich. They pay a high proportion of their income to the banks.
If you were among the poor, getting out of the ERM and not joining the Euro is a bad decision. If you own shares and houses, then not joining the Euro is a good decision.