The Tory and Labour leaders declined the channel’s invite, leaving the five other leaders to debate in the first televised clash of this election.
Ahead of the debate in Salford, Peston was on ITV News At Six promoting the clash that was due to kick off an hour later.
When asked about Corbyn and May’s no-show, Peston said: “Well, many of us would say it’s pathetic but we’re still gonna have a really gripping debate about the priorities needed for this country.”
He then gleefully tweeted about it, saying: “Did I just call Theresa May and Jeremy Corbyn pathetic on live TV? That might have happened.”
While Tim Farron, Paul Nuttall, Nicola Sturgeon, Leanne Wood and Caroline Lucas argued on stage, Twitter lamented the absence of the leaders of the largest two parties, the only people with any chance of becoming prime minister after the election.
May has avoided a direct debate with other leaders. She is due to face questions from Jeremy Paxman and grilling from a live studio audience - but only after Corbyn, not alongside him.
May, who is expected to win a large majority at this election, has said: “I don’t think people get much out of seeing politicians having a go at each other.”