It is not true that Jeremy Corbyn and Theresa May were not present at last night’s minority party debate on television. They were not there in person, but they were well represented by those who were.

A grand fiction of British general elections is that they are multi-party affairs. Since the dawn of the universal franchise they have been a fight between Labour and Conservative. In good times or bad, under good or bad leaders, they have never been anything else, however much the media and pollsters pump up the “minority party” effect. Minorities are supposed to “steal votes” from the two big parties. They are dustbins for the disgruntled. They are always a “threat”.

They are not. Labour was last night represented by Ukip’s leader Paul Nuttall. How many normal Tory voters could he persuade not to vote for May? The prospect is of a decreasing number, though admittedly countered by the normal Labour voters he may take from Corbyn. For the Tories, however, the evening was a bonanza. On stage were four left-of-centre parties, the Greens and Liberal Democrats and the two nationalists, all out to take votes from Labour. Since the election is for a UK-wide government, a vote for Scottish and Welsh nationalism in Scotland and Wales is savagely anti-Labour. In England, the Liberal Democrats and Greens perform the same function.

All parliamentary elections for national governments are proxies for presidential ones. They date from a surely defunct territorial idea of representative government. The pretence is that a local first-past-the-post vote is somehow a proxy for a national poll. This yields such profoundly undemocratic absurdities as the winner sometimes scoring fewer votes than the loser (as also in America’s electoral college), and of large numbers of votes being in effect wasted. This gives an incentive to constituency gerrymandering and vote rigging.

All a minority party can do locally is give one of the big parties a leg up, by choosing which side to split. The “progressive” political outlook of today’s Greens and Lib Dems is hardly different from Labour. Their inability to forge local alliances – not even with the nationalists in Wales – does not render them useless. It makes them Toryism’s useful idiots.