The Great Muppet Caper(1981)
The second movie of the Muppets.
In this movie, Kermit the Frog, Fozzie Bear, and Gonzo are newspaper writers, and Miss Piggy is Fashion Maker and the rest in the "Happiness Hotel". When Fozzie, Kermit and Gonzo get chewed out by their boss for not getting a picture and a story of a thief robbing Lady Holliday of her jewels, The trio agree to go to London and find the crook and bring him to justice. Having reached London, and getting rooms at the Happiness Hotel, Kermit decides to go interview Lady Holliday about the jewel theft but accidentally interviews Miss Piggy instead(he thinks she is Lady Holiday). After another robbery and Miss Piggy gettting framed for it, the entire muppet gang decides to catch the real crooks red-handed.
This is the Columbia/TriStar Home Video trailer for the movie.