1974 All Over Again?

If the Lib Dems go into the next General Election promising a referendum on EU membership, then will columnists such as Simon Heffer (Enoch Powell's biographer), Andrew Alexander (Powell's close friend) and Peter Hitchens do an Enoch, and call on their readers to vote Lib Dem? If not, why not? And if so, then what would the Lib Dems have to say in response to such endorsements?