He quizzed her on a secret Labour report leaked yesterday that called for the party to "atone for its past" and branded Ed Miliband a "weak and bumbling leader".
"We have got to listen to what the public's been saying to us," Kendall told him.
"This report confirms what many of us heard when we were out on the doorstep campaigning in marginal seats: people didn't trust us on the economy or their taxes."
But signing off the interview, Peston confused the name of his interviewee with her rival and winner of the Labour leadership contest, Jeremy Corbyn.
"Liz Corbyn, many thanks," he said before a look of utter horror struck his face.
Kendall could only wince and smile.
Something she's plenty used to doing at ITV cameras...