The surprise was that it is actually quite good.
Simon Pegg studied drama at university but earned his spurs in working life as a stand-up comedian. Which perhaps explains why his timing is so split-second perfect. The gags in Run, Fat Boy, Run are not that remarkable. At times you can even see them coming. But the performance and skillful delivery is so polished that they are entertaining anyway.
Run, Fat Boy, Run uses a formula that has served Pegg and his growing fan base well: he is the nerd who eventually turns hero. We feel sorry for him, irritated by him, repelled by him. He's the well-meaning hopeless case we just want to 'fix'. So the audience is relieved and rooting for him by the time he makes good. We are fully behind him by the time he makes his resolve that he is "sick of being a 'nearly-man'." In this present incarnation, Pegg (Dennis) has an attack of nerves just before getting married. He runs out on his gorgeous wife-to-be Libby (played by Thandie Newton) - literally - running off as she stands in the road in full bridal dress. And pregnant.
Five years later, Dennis is working as a security guard at a women's clothing store. The predictable jokes are spoon-fed us faultlessly. Pegg rescues any situation that threatens to become too silly by a look of open sincerity (rather like Ricky Gervais does with political humour). But Pegg seems to have an instinctual grasp of cinema that enables him to extract the best results from his material. On a hot Saturday afternoon, and with strong competition from much publicised movies, the auditorium was fairly packed.
The second theme from the film's title comes from Dennis' decision to run the London marathon. This is mostly to 'prove' something to Libby (for whom he has now discovered undying love) but also to win a bet for his mates and to prove himself equal to Libby's super-fit, super-rich, super-handsome suitor, Whit. His five-year old son provides the magic glue to pull all the elements of the story together.
In a wise choice, the filmmakers avoid anything that might belittle the Marathon (given that many UK viewers may have a deep respect for the institution). But they also bring in much underused and very photogenic shots of London en-route - particularly the Docklands area.
With such a vanilla story line, Run, Fat Boy, Run is relying on Pegg's reputation to pull in audiences. I suspect that many of his fans may be occasional movie-goers who simply demand something light and untaxing. He has the ability to make a futile chase after stolen women's underwear amusing. When he seems to be rubbing himself off against a shop mannequin it could be a pathetic or tacky sketch in any other hands, but his wide-eyed expression and fast pacing move us from one joke to the next before we have time to analyse.
I wasn't bored. And I had expected to be. In fact I was laughing loudly. It reminded me of when JM Barrie had planted children in the audience of his first performance of Peter Pan. It helps to be in the company of people who see the joke. Run, Fat Boy, Run has not made me a convert to Pegg's brand of humour even if I enjoyed the film, but I have to admit that he is good at his job. Sometimes it is the difference between a sterile press screening and an audience of fans. On this occasion, marketing gets the benefit of the doubt.