There's a certain tension at the heart of every good theme park. As a park owner, you naturally want your punters to have a good time. But as a currency, smiles and laughter only go so far. At some stage, you're going to need them to open their wallets. "It's like a John Lewis advert, right?" says John Laws, art director at Frontier Developments. "I get the exact same feeling when I see the John Lewis advert at the end of each year: 'Oh, that's really nice production design, better than most other ads'. And ultimately they just want me to spend money. But I don't care, because it's nice to watch."