Mexico has no run-off vote, so people wishing to vote tactically against the PRI must do so first time, on July 1st.

ECONOMIST: A much-watched debate fails to shake the front-runner

Labour voters would not then have to agonise over whether to cast their votes for the deserving Mr Davies or to vote tactically for Mr Oaten.

ECONOMIST: Historic Winchester

Though Fianna Fail's vote went up by just 0.2%, clever tactical voting produced a sharp rise in seats, while the tactically dimmer Progressive Democrats held their vote but halved their seats (though a resentful recount is going on over a Dublin seat lost to a Green).

ECONOMIST: Ireland