Steve Pratt sees Ricky Gervais and Ben Stiller make an exhibition of themselves for Night At The Museum 2

THE law of press junkets states that if you put two comedians in the same room they’re rarely twice as funny as having a single comedian there. And so it is when Ben Stiller and Ricky Gervais are reunited to promote their movie Night At The Museum 2.

Not only have they shared screen time in the first Night At The Museum but Stiller guested as a ego-driven director in the first episode of TV’s Extras, the series with which Gervais followed the runaway success of The Office.

While Gervais is jokey and jovial in person, Stiller is more thoughtful and serious in his answers. That’s especially true concerning the monkey. Dexter the capuchin monkey from the first Museum movie returns for more faceslapping antics at the expense of Stiller’s character.

“I’m beyond tired of the monkey, I resent it, I want to kill the monkey,” says Stiller with mock seriousness.

Gervais finds all this very amusing, adding “There’s the headline.”

Stiller hasn’t finished talking about the scene that finds two Brazilian primates, Squirt and Crystal, playing not only Dexter but Able, the space monkey in the Smithsonian Institution.

“No, monkey-slapping day wasn’t the most exciting day of the shoot for me,” he says before turning to his human co-star and saying, “I’d rather do scenes with you.”

Night At The Museum continues the idea that exhibits come to life after dark once the place is closed for the night. Stiller plays former security guard Larry who comes to the rescue of his exhibit friends when they’re threatened with being put in storage. Gervais appears briefly as the museum director.

“We had to figure a way to start the second movie because everyone was so happy at the end of the first one,” explains Stiller, whose Tropical Thunder comedy was one of the biggest hits of last summer.

“The idea is that Larry had become successful and all the problems that come with success had drawn him away from his true happiness. Success doesn’t necessarily mean happiness.”

Gervais butts in with a “Yeah, I did the sequel for the money”, which gets a laugh.

As for a third, should the box office numbers justify them getting together again, Stiller doesn’t know.

“The idea of doing a third one would be great, it’s just figuring out how it could get any bigger, any different. If indeed it seems like enough people wanted to see a third one,” he says.

One reason why Stiller was pleased to see Gervais was that he’s spent weeks acting by himself, imagining dinosaurs and suchlike coming to life in the knowledge they’d be inserted later through computer trickery.

“I was very glad he showed up because it had been weeks and weeks acting with nothing. Like running away from a dinosaur when there was no dinosaur, or running away from Attila the Hun and there’s no one there, no people to interact with. Then Ricky showed up one day,” he says.

“Oh, I see, I’m better than nothing,” says Gervais, pretending to be hurt.

Despite having company, Stiller found his British co-star almost too much. No wonder, for Gervais admits trying to wind him up. “The best part of being Dr McPhee was trying to be so strange as to really put Ben off. That was the most fun in the world,” he says.

“The characters just got madder and madder to the point where Ben stopped the take we were doing and said, ‘that’s just ridiculous’. And do you know that’s the nicest thing anyone has ever said to me.”

Stiller explains what happened.

“He just went off on this crazy tangent. About what my character was probably thinking and saying, and it was like so far from reality, there was no motivation for it whatsoever. I just had to say something. “But we did laugh a lot.

Of course, it’s in Ricky’s contract.

He’ll turn up for 12 hours to do all his work – and that’s it for all two movies.”

Another of Stiller’s co-stars was a very different prospect to funny man Gervais – George Foreman, the former world heavyweight boxing champion more famous now for selling his grills. He appears in a sequence in which Stiller’s character films a commercial. “He took direction, he was great,”

he says of Foreman.

“I was in awe because it was George Foreman. It was also one of those cool things. You have this idea, let’s do an infomercial and let’s do it with George Foreman.

And then it happened, all of a sudden George Foreman is there. He was so great and nice and positive and big.”

He was also pleased to film at the Smithsonian Institution in Washington DC because it was always his favourite museum. “I’ll always remember going there as a kid because they had the USS Enterprise from Star Trek there,” he says.

■ Night At The Museum 2 (PG) is in cinemas now.