On a February afternoon, mainland visitor Li Xiabo sits down to pork and rice at a bustling outdoor cafe in Ocean Park. At the next table is a Hong Kong customer. His food is the same. The portion size is the same. In fact, the only difference is the price the two customers paid for their meals. While the Hong Kong customer paid HK$45 for his lunch, Mr Li paid the equivalent of HK$51.70. And whether he is aware of it or not, from the start to the finish of his visit to the theme park, Mr Li will pay a hefty surcharge of about 13 per cent for everything he buys compared to the price paid by the man at the next table. The reason for the disparity is simple: Mr Li - like hundreds of thousands of mainlanders a year at Ocean Park - paid for his meal in the cash of his home currency, the yuan. Hailed as a convenience for the growing number of mainlanders pouring into Hong Kong, the dual-currency approach appears to have become a method of increasing profit margins by stealth. Ocean Park and Disneyland - in common with a number of big shops and department stores in Hong Kong - were last week offering a one-to-one exchange rate for customers paying in yuan even though 100 yuan was worth more than HK$113 at official rates. When told of the practice, both the chairman of the Hong Kong Tourism Board and the legislator representing the tourism sector described it as unfair and damaging to Hong Kong's image and called for a better deal to be offered to mainland visitors. However, the theme parks and the shops with the one-to-one exchange rate - at a time when tourism numbers are falling and the government is working hard to attract more mainlanders - defended the policy, indicating they had no immediate plans to accept yuan at levels closer to the official rate. In practical terms, the effect of the one-to-one rate is that when Mr Li handed over a 50 yuan note for his HK$45 meal, and was then given change in Hong Kong dollars, his bill had cost him the equivalent of HK$6.70 more than the Hong Kong customer at the next table. It might sound a trifling amount - but for Mr Li and mainland visitors every day, the extra bucks on a bowl of rice are just one item on a long shopping list of surcharges that can potentially add hundreds or even thousands of yuan to the cost of a stay in Hong Kong. If Mr Li paid for his admission, too, in yuan, handing over 300 yuan for the HK$208 adult entrance fee and receiving HK$92 in change, he would have paid the equivalent of around HK$248 to enter - HK$40 more than the advertised price. For anyone who uses yuan throughout their Hong Kong stay, losses can multiply if they decide to call in on Disneyland or indulge in a spot of brand-name shopping. At Disneyland, hand over 400 yuan for an adult ticket priced at HK$350, and you will end up paying the equivalent of around HK$415 to get in - HK$65 over the advertised price. And that's before buying a single souvenir or soft drink. The theme parks are not alone. Big-name fashion stores including Lane Crawford in Pacific Place, the Sogo department store in Causeway Bay and restaurants including the Spaghetti House chain have the same policy. So if someone uses yuan to buy a HK$600 meal for two in Spaghetti House, they end up paying about HK$680. Surprisingly, the Hong Kong Tourism Board says it has yet to receive a single complaint about the one-to-one exchange rate offered at so many places. But that does not mean the practice is acceptable, according to board chairman James Tien Pei-chun, who said it was a matter not just of money but of fairness. 'This is damaging to Hong Kong's image,' he said. 'Hong Kong is a cosmopolitan city and people should feel when they come to visit that we are fair and that we aren't taking advantage of people over little things. 'If people see an organisation like Disneyland taking advantage and charging the equivalent of around HK$400 for admission when the price should be HK$350, it will hurt Hong Kong's image.' This is an edited version of an article which was published in the Sunday Morning Post, March 1, 2009.