SPB, Labour and Lib Dems all supported having the 2016 referendum too.
They both promised it in their manifestos.

DMcG, the horsemeat scandal started in Eire and spread to 13 EU countries. It is irrelevant to the issue of the border, except it might have been harder to get the bad meat into Britain if we were outside EU.

There is nothing to stop such crime occurring now so Brexit will not make it any more likely.