Vote Mebyon Kernow
Vote Respect. In
And I suppose, if there really, really is no other option, Charles Kennedy's lot will have to do, as in the constituency of Cornwall North, where other than the Lib Dems, the only anti-war vote available is for Dick Cole, the leader of Mebyon Kernow, the hick Cornish irredentists whose main political activity seems to be painting over the English rose on brown tourist attraction road signs on trunk roads in the Southwest and replacing it with the cross of St. Piran.
If your're confused, Red Pepper's put together a good guide to how to vote left in the UK. Although they really do call for a vote for Mebyon Kernow.