Generally, people should not engage in tactical voting, which is different from two parties coming to an agreement. People should vote for what they believe in for the sake of the message the result sends and for the future of the party which they truly support, locally as well as nationally.
This applies here in Newcastle about voting Liberal Democrat because the other parties are not Remain parties, including Labour.
The voice of Remain needs to be clearly represented especially since we find ourselves in a general election and have not had a people’s vote. In any case we now have the Brexit Party for Leavers as well as the Conservative Party.