It's not unusual for sitcom families to go on a big vacation together, but ABC's Speechless is probably the first to take characters who are essentially homeless and put them on a plane to London.

Yet how else were they going to meet John Cleese, who makes his sardonic entrance about halfway through Friday's third-season premiere?

As the network this week moves Speechless and Fresh off the Boat, another of its family-focused sitcoms, to Fridays, the 78-year-old British comedy legend guest-stars in a two-part episode as Martin, the father from whom Maya DiMeo (Minnie Driver) has been long estranged.

"He's so amazing," Micah Fowler said of Cleese in an interview during an ABC event in August. Fowler, of Barnegat Township, N.J., plays the DiMeos' oldest child, JJ, and, like his character, he has cerebral palsy. (Unlike JJ, who uses a communication board, Fowler speaks, though with occasional difficulty.)

Cleese was a delight, said John Ross Bowie, who plays JJ's father, Jimmy DiMeo, whose job at an airline made the financially strapped family's trip to seek a loan from Cleese's character at least moderately plausible.

"He was really fun to work with. He really liked the material. It was really nice to be doing this show, and to be working with an icon like Cleese, and to see that he clearly enjoyed the writing as much as we do," said Bowie, who's also had a recurring role as string theorist Barry Kripke on CBS's The Big Bang Theory. "I knew it was good — but we now have someone from [Monty] Python validating it. That puts a little wind at my back, I won't lie to you."

The 20-year-old Fowler, who saw Hamilton for the first time in London ("Every single person in that cast was amazing"), acknowledged not having seen much of Monty Python's comedy while growing up.

Bowie said he intends to rectify that.

"I'd start with the TV show [Monty  Python's Flying Circus], and then I'm going to do [Monty Python and the] Holy Grail — and then I'm going to check with his parents," he said.

John Ross Bowie (second from left), Mason Cook, Micah Fowler, and Kyla Kennedy in a scene from the London-based season premiere of ABC’s “Speechless.”
Angus Young/ABC
John Ross Bowie (second from left), Mason Cook, Micah Fowler, and Kyla Kennedy in a scene from the London-based season premiere of ABC’s “Speechless.”

For Speechless creator Scott Silveri, who last season left the DiMeo family stranded with their possessions on the front lawn of the home from which they'd just been evicted, getting to work with Cleese is one of the payoffs of an even bigger gamble than his characters are taking. ABC hadn't yet picked up the show for a third season when that episode was filmed.

"We were hopeful, we were confident, but we didn't know. At the same time, I didn't want to write something that would put it all to rest and have them say, 'OK, all done. We're satisfied. We don't need to make any more of these,' " Silveri said, adding, laughing, "You want to leave them with something that if this is how it's going to end, people are going to storm the gates of the network."

As for London, "I'm no actor, but to play it cool in front of John Cleese for three days was the hardest performance I've ever had to put on. As he would say things like, 'Are you familiar with the hotel show?' 'Fawlty Towers? Yeah, I've heard of it,' " the former Friends writer said.

"I managed not to geek out too much, and we established a very nice rapport. And he had such an easy chemistry with Minnie, and with the cast, that it just felt like a really good version of a Speechless episode, rather than turning over the series to a genius. If you're going to turn it over to anyone, he's the guy you want to turn it over to, but I think we managed to find something that was, you know, quintessentially ours, and find something new with him together," Silveri said.

"The whole point was to flesh out Minnie's character a little more, get a little sense of where she came from. And he gave us the gift of allowing us to do that in a really, really funny way."

But then, if not for the decision a few years ago to have the London-born Driver use her own accent, the trip abroad might never have happened.

Driver has "a great American accent, but it's sometimes tough in comedy to modulate that. And you don't want any stink of inauthenticity at all. So what we did for the pilot was we read it both ways," Silveri said. "Not only was the British one, I think, funnier, it was three minutes shorter, so, OK! Three minutes of free jokes, we're going to go British!"

Watch this

Speechless. 8:30 p.m. Friday, ABC.