Every year since I can remember, it seems something has been killing Christmas: commercialism; multiculturalism; secularism; or that political correctness of the “gone mad” variety that they have now. This is not a new idea. An ancient cave daub, dating from 10,000 BC, on the walls of the Grotte de Niaux in southern France, appears to show a Neolithic man tutting at a cave child who has ignored a perfectly serviceable flint in order to play with the leaf it came packaged in. Like an elderly Christmas reindeer that can no longer illuminate its own nose, Christmas continues to cling to life, damp December tinsel fluttering in a February gutter. But this year, I feel the fatal body blow may finally have been dealt.

On 16 November, the three members of the shamed defensive tax planning unit Take That arrived in London to turn on the Regent Street Christmas lights. This year the Christmas lights take as their theme the third film in the successful Night at the Museum franchise, Night at the Museum 3: Secret of the Tomb. And nothing says Christmas like a trio of broken dead-eyed tax-avoiding husks pulling on an imitation joystick purporting to throw into life dozens of enormous illuminated images of Ben Stiller’s face, hanging obscenely in the once empty air, a stale and unprofitable space between the buildings, now at last actively monetised, thank Christ. Merry Christmas. Merry Christmas. God bless us everyone.

Stiller, the star of Night at the Museum 3: Secret of the Tomb, is in town to promote Night at the Museum 3 : Secret of the Tomb. Stiller and I have mutual acquaintances, principally in the podcasting community admittedly, but I ask his people if I can meet him, cynically hoping he will say something facile about London’s festive Night at the Museum 3: Secret of the Tomb Christmas lights that I can spin out into a space-occupying Observer column.

Stiller elects to meet at a Soho pancake joint. The comedian is, it turns out, obsessed with pancakes, confessing, “It’s the one vice I have left. As soon as I get to a new city I say to the runner, ‘Show me the pancakes’. I like to go to a new pancake store and sniff each of the pancakes in turn before I choose one. If I could die and come back as a pancake I would. I wish my nutsack was full of pancake mix so I could make my own on demand. Christine made undershorts out of pancakes at Thanksgiving. I felt really happy wearing them but in the end they just weren’t practical and after a few days they rotted away. C’est la vie, my friend, c’est la fucking vie already.”

Stiller, dressed casually in trousers, socks, shoes, underpants, shirt, jumper and jacket, orders a large plain pancake with no syrup, and a mug of pancake mix, which he downs in one, slamming the mug hard on the table afterwards like a shot glass. “Hoo hah!” he shouts, sweating and suddenly agitated, “Bisquick!” Stiller wipes stray mix off his lips using his uneaten pancake as a napkin, and clicks his fingers to the waitress for more mix. “Do you think maybe you could warm it up this time, honey, if it’s not too much trouble?”, he barks, Hollywood style, before turning his ire on me.

“Don’t think I don’t know why you’ve brought me here, Stew Art,” he begins. “You think I’m a joke, don’t you, Mr Too-Cool-For-School? I’m the once radical innovator of Reality Bites and The Ben Stiller Show, the comedy voice of Generation X, reduced to shilling for serving three of a mainstream movie franchise that appears to have done a marketing tie-in deal with a major religious festival. That’s what you think. Well, do I look that dumb to you, I mean do I? Maybe, just maybe, I’ve been playing a long game.”

The pancake mix, warm this time, arrives, and as Stiller drinks it down, staring at me, he continues between hearty gulps. “Ben Stiller is in the mainstream now Stew Art,” he whispers, menacingly, “in deep. And the power and influence this position affords Ben Stiller has allowed Ben Stiller to embark upon the first of a series of pornographic spectacles which, when viewed through the lens of history, will reveal Ben Stiller as the greatest satirist that ever lived, a person whose very life became a conscious commentary on global corruption. More mix!”

The pancake mix arrives. Stiller barks at me, “What’s my most famous scene?” I hesitate. “Say it. Don’t be ashamed.” “Well,” I admit sheepishly, “it’s when your penis gets trapped in your flies in that film.” “That’s right it is,” he agrees, “and you know what, I played it brilliantly. I tried to make a face that wouldn’t preclude my character being either circumcised, or uncircumcised, so the scene would play for maximum comic effect in all territories, irrespective of their penis traditions.” “Yes, I’d often thought you must be doing that,” I agreed, “it’s very clever.”

“It is clever,” Stiller reiterates, “But I know that when people look up in London and see the Night at the Museum 3: Secret of the Tomb Christmas lights they aren’t going to be thinking about peace on earth, a goodwill to all men, and all that jizz. No, like it or not, they’re going to be thinking about a guy’s schlong trapped in his zipper. I just torpedoed Christmas. And you deserve it. You say Christmas is dead, and you blame immigrants, and imaginary liberal cabals imposing non-existent PC dictats, but all along it was capitalism, man. And now I’ve engineered a situation that ought to make that totally obvious, holding up the mirror to your corruption, but you’re so blind.”

“So you’re living your whole life henceforth, the promotional duties, the lights, as a satirical critique that will only make sense in the future? You’re masterminding everything?” I ask. “Not everything, Stew Art,” Stiller replies. “Sometimes a creative talent like me sets an idea in motion and it takes on a life of its own. I didn’t ask for three tax avoiders to throw the switch. London chose Take That. But it’s too too perfect. If I’d planned that it would have seemed too heavy-handed, sledgehammer subtle. But London chose Take That, and with no sense of it being the crowning obscenity. Some days you’re just lucky, I guess. Try the pancake mix. It’s delicious.”

Stewart Lee’s Comedy Vehicle (series 3) DVD is out now and tickets for 2015 tour dates are on sale at stewartlee.co.uk