Over the past 150 years, monetary policy in Hong Kong has centred on developing a reliable and stable currency to meet the needs of a rapidly expanding trading centre. This has not always been an easy task. When the British colonised Hong Kong in 1841, China bimetallic monetary system operated on two levels: copper, bronze or iron cash were used for the smaller day-to-day transactions; uncoined silver ingots were used for larger business transactions, paying taxes, and storing wealth. In addition, Spanish and Mexican silver dollars were used for international trade. The beginnings of Hong Kong's monetary system The early colonial government in Hong Kong made sporadic attempts to promote the British pound sterling as Hong Kong's official currency. But because of Hong Kong's special position as a trading centre, a variety of currencies, including the silver dollar, the Indian rupee and the Chinese cash, became legal tender. The pound sterling, a gold-based currency, was unfamiliar, unpopular, and in short supply. The government found it impossible even to collect revenue in sterling, and, in 1863, finally declared the silver dollar to be the only legal tender. A Hong Kong version of the silver dollar was issued in 1866.