How can TV debates possibly be fair in politics?

Jo Swinson has been left out. Yet the line-up in TV debates has to be a compromise, based on what we know of levels of support and likely outcomes

Liberal Democrat leader Jo Swinson at the party’s autumn conference in Bournemouth (PA)

It is unfair that Jo Swinson has been cut out of the first TV debate of this election campaign. ITV has announced that Boris Johnson and Jeremy Corbyn will go up against each other, just the two of them, on 19 November.

The company says other party leaders will be able to take part in another programme “later that same evening”, and that it plans a seven-way debate with leaders or “senior figures” representing all the main parties.

The Liberal Democrats are justifiably furious, but there is no “fair” answer to this question. It is reasonable for the broadcasters to say that there are only two people likely to emerge from the election as prime minister.