Task: Question Answering
Input (English): Bound for a London show, the Beatles escape a horde of fans. Once they are aboard the train and trying to relax, various interruptions test their patience: after a dalliance with a female passenger, Paul's grandfather is confined to the guard's van and the four lads join him there to keep him company. John, Paul, George, and Ringo play a card game, entertaining schoolgirls before arriving at their destination.Upon arrival in London, the Beatles are driven to a hotel, only to feel trapped inside. After a night out during which Paul's grandfather causes minor trouble at a casino, the group is taken to the theatre where their performance is to be televised. The preparations are lengthy so Ringo decides to spend some time alone reading a book. Paul's grandfather, a "villain, a real mixer", convinces him to go outside to experience life rather than reading books. Ringo goes off by himself. He tries to have a quiet drink in a pub, walks alongside a canal and rides a bicycle along a railway station platform.[5] Meanwhile, the rest of the band frantically (and unsuccessfully) attempts to find Ringo. Finally, he returns after being arrested by the police along with Paul's grandfather, and the concert goes ahead as planned. After the concert, the band is taken away from the hordes of fans via helicopter.[6], Question: Who's grandfather caused trouble at the casino?
Output (English): Answer: Paul's.