Ian Hislop has compared Boris Johnson with a tub of lard - joking that until recently he thought the lard had a better chance of becoming prime minister.
The Have I Got News For You team captain was referring to a 1993 episode of the BBC One show, in which Labour MP Roy Hattersley was replaced by a tub of lard, credited as The Rt Hon Tub of Lard MP, after three last-minute cancellations.
Mr Hislop, 59, is a regular critic of Mr Johnson, 55, who became leader of the Conservative Party in July.
He joked that while he was "amazed" Mr Johnson had got the top job, the Prime Minister was probably equally surprised.
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Mr Hislop, who is also editor of the satirical Private Eye magazine, is returning alongside Paul Merton for the 58th series of HIGNFY on BBC One.
He said: "I'm amazed he's Prime Minister and I think he's probably amazed he's Prime Minister.
"Of all our guests over the years I thought it was more likely that the tub of lard would become prime minister - and so he has you might argue - but I am not going to say that because that sort of unpleasant language is best left to MPs.
"It's extraordinary. I mean, he's only just Prime Minister. I never thought it would happen, but since it has happened, nothing that's happened since has surprised me."
Mr Hislop also took aim at the PM's recent decision to suspend Parliament, which was later found to be unlawful.
He added: "He's been slapped down by the Supreme Court for acting unconstitutionally and unlawfully and giving unlawful advice to the Queen, for which he had to apologise.
"Although the Queen isn't the first angry woman he has had to apologise to.
"He does tend to have to apologise throughout his career, and as I said in the last series, when the producers cut it out and put a black box over my mouth on the broadcast, Boris Johnson has built a career on telling porky pies.
"He was even caught out telling porky pies about pork pies. It's a surprise he's there, but just how shambolic, extraordinary, reckless and chaotic the situation is, doesn't surprise me."
Mr Hislop also revealed that his ideal guest on HIGNFY would be Lady Hale, the president of the Supreme Court.
Lady Hale, 74, delivered the judgment that found Mr Johnson's decision to suspend Parliament to be unlawful.
After the judgment, during which she wore a large spider brooch, social media users hailed her as "spider woman".
Mr Hislop said: "Lady Hale, now that's my ideal guest. You know, spider woman.
"I think she'd be very good in the chair.
"Once you've done the hosting job in the Supreme Court, I think there's nowhere else to go... and she'll be very impartial, I'm sure. As I am."
Have I Got News For You returns to BBC One on Friday October 11 at 9pm.
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