There will be televised debates in 2019. Probably.

ITV has announced that it will a hold a head-to-head debate between Boris Johnson and Jeremy Corbyn on 19 November. For Johnson, the debate comes with a heavy risk — but with a hell of a prize attached. The heavy risk is that Johnson does not do well in these debate formats — he did poorly against Ken Livingstone in 2008 and 2012, poorly against Jeremy Hunt in the leadership hustings, and was anonymous in the BBC hustings for the Tory leadership, though that last was as much due to the format as anything else.

Added to that, Corbyn tends to do pretty well at such times. He has a lot of experience in this format, having done many debates throughout his political life, and came out top in the vast majority of the hustings for the Labour leadership, most significantly the BBC debate where he introduced himself to the majority of Labour members. It was in that debate that he first took the lead among Labour activists — a position he has never relinquished since.

Johnson struggled for long periods against Hunt and only really managed to come out on top when he adopted a very bullying style which worked pretty well as far as the debate audience were concerned. But Hunt, a slick, well-spoken and very posh man, perhaps made the ideal victim — doing the same against a man who is visibly older than him might backfire.

For Corbyn, it is win-win. He’s good at these debates and anything which frames the election as a choice between him and Johnson will ease at least somewhat his difficulties with the Liberal Democrats and Greens. So what’s in it for Johnson?

The prize on offer for the Prime Minister is twofold: firstly, it benefits him as well as Corbyn to shut out Jo Swinson, whose Liberal Democrats are a major threat to the Tories across much of England, and shuts out Nigel Farage too. Secondly, it could possibly concentrate the minds of voters on the question of which one of Johnson or Corbyn they want in Downing Street: a question on which, at the moment, Johnson leads Corbyn on by double digits.

There are a couple of additional risks. The first is that, if the debate were held tomorrow, anything which frames the election as a choice between Johnson and Corbyn is good news for the PM. But what if, in three weeks, Corbyn’s ratings are again recovering and asking voters which one of the two they want in Downing Street is no longer the slam-dunk it is at present?

The second is that the Liberal Democrats may yet spoil the party. That party has long been of the view that having gained more than 700 councillors in May, finished second in the European elections and with a poll rating equivalent to their opinion poll standing at the start of 2010, when Nick Clegg attended the same number of TV debates as Gordon Brown and David Cameron, that they have a right to attend every televised debate — and that they will force their way in, whether via Ofcom or the courts. That could yet mean that the televised debates don’t go ahead - or worse, that they go ahead, and he ends up facing not one but two tricky opponents without even the prize of turning the election into a choice between him and Corbyn.