Tactical vote will deliver knockout blow to PM, say Lib Dems as poll race tightens

Ed Davey calls on Labour and Green voters to switch in Devon seat where result is too close to call

Liberal Democrat leader Sir Ed Davey has appealed to Labour and Green party supporters to vote tactically in Thursday's crucial West Country byelection - to help deliver a knockout" blow to Boris Johnson's premiership.

The Lib Dems believe they have a realistic chance of causing one of the biggest byelection shocks of recent times by coming from third place to win in the normally safe Conservative stronghold of Tiverton and Honiton.