Sewers and public toilets aren't exactly appealing sights, but highlighted on an 1882 map of Hong Kong they are a quirky feature. 'The map came with the Chadwick report on sanitation and water supply and as a result of its recommendations, the impressive Tai Tam reservoir was built,' says Jonathan Wattis. The founder of Wattis Fine Art didn't just acquire the lithograph map for his gallery; he also ploughed through the dense report. 'It was hard going, but it's an important part of Hong Kong history,' he says. Such efforts have given Wattis an in-depth knowledge of the early history of the city and the Pearl River Delta that has earned his business in rare maps, photographs, books and prints a measure of fame in Asia. Wattis' gallery on Hollywood Road marks its 20th anniversary this week and historian Nigel Cameron says it has become a vital part of the neighbourhood known for its art and antique shops. 'It's important to have a few galleries that focus on historical art related to Asia and Wattis is one of the recognised best dealers in Hong Kong,' Cameron says. 'The gallery reflects the knowledge and experience of Wattis himself.' An affable man with a fondness for bow ties, Wattis, 52, says he has always loved history and literature. He applied to join Christie's rare books department soon after leaving school, but was assigned to the ceramics division instead. That turned out to be a blessing because it widened his perspective. 'It was an Aladdin's cave of ceramics from China and Japan as well as European countries,' he says. 'I learned about the style and history of different cultures.' His bosses initially had him sweep the floors, but by the time Wattis left to travel around Asia six years later, he had become a specialist. 'I learned to do an immense amount of research because I had to convince 70-year-olds that I knew what I was talking about,' he says. Wattis planned a brief stay when he landed in Hong Kong in 1984 but, like many expatriates, he saw a business opportunity and stayed. 'The arts scene then was narrow. I could count the galleries around on one hand,' he says. He started with a 'cupboard-sized' art gallery on On Hing Terrace in 1985 before moving to the Hollywood Road premises three years later. But as more galleries offering contemporary art popped up, Wattis drew on his expertise and contacts in the antiques business to specialise in books and objects related to east-west trade from the 16th century to the 1950s. Among the most memorable maps he dealt with is a proof of the first Belcher survey of Hong Kong in 1841. 'There's a Mount Possession, which later became Victoria Peak and a 'highest peak' which wasn't really the highest,' he says. Tracking objects in private collections requires patience. For instance, Wattis spotted the Belcher survey map in a collector's office in the 1990s and waited for years until the owner was ready to sell. Still, his talent for research and building a narrative around the displays in the gallery undoubtedly give him an edge. Waving at a watercolour that he believes was painted by British surveyor Thomas Bernard Collinson in 1843, Wattis points out the fenced compound of the jail on the site of what later became Victoria Prison and an upper bazaar area that probably became Peel and Graham streets. 'The issue over the markets now is interesting because they were one of the first areas to be built. In Kowloon, in what would become Ocean Terminal, there are a few huts on the beach,' he says. 'By putting together these images, you get a unique view of early Hong Kong that few records might hint at.' A keen traveller as well as a history buff, he often delves into his personal library of rare books before a holiday. 'I read about the historical context of the place I'm visiting; not just the latest guide books, but also books going back to the 1800s that would give me a sense of history of the place,' Wattis says. His diligence and enthusiasm has nurtured a base of loyal clients, including writer Valery Garrett, who began tapping the gallery for reference material 14 years ago when she was working on a book on the history of Guangzhou. 'Wattis loves what he does, but at the same time he has a really deep knowledge of his stock and what's out there, and puts that across in an engaging manner,' Garrett says. Collectors' interests have shifted over the past two decades. Ahead of the handover, nostalgic items were the most sought after. 'I couldn't get my hands on enough material to meet demand,' Wattis says. Among the most popular of these items was an illustrated sporting map by cartoonist Friedrich Schiff in 1938 featuring figures of women sunbathing at Repulse Bay, dapper golfers teeing off near Shek O and couples dancing at a Central club. A print hung in the gallery window attracted dozens daily, he says. Not surprisingly documents dealing with Macau are now attracting more interest, and one of his finds is a coloured plan of the former Portuguese enclave dated 1796, showing the forts, parishes, colleges, convents and chapels. 'But the difficulty is finding something different because it's a small place and there's only a finite amount of material available,' Wattis says. Private collectors remain important, but these days the gallery derives much of its business from museums, libraries and universities around the world - including the mainland. 'I could be based in London or New York because my sources and clients are global,' Wattis says. 'But I specialise in this part of the world, so it makes sense to be here.' The internet has changed the trade, making the gallery accessible to more customers and broadening their choices. 'A number of people come to the exhibitions, ask questions and then compare prices on the internet,' Wattis says. He is getting more competition from young Hongkongers entering the niche business. 'The trade does need young people; it raises awareness,' Wattis says. But newcomers must have the knowledge to earn clients' respect. 'They have to know that they're getting the right thing,' he says. That's why Wattis hasn't expanded to other cities despite receiving several invitations. He and his wife Vicky run the gallery themselves, doing everything from posting invitations to mopping the floor. 'We're often in the gallery until 8pm and, if I'm researching something, I could take the book with me to bed,' he says. 'We have to work very hard to maintain the business, but the upside is that we're surrounded by beautiful things and I meet a lot of very talented people.' The carefully preserved visitors' books at the gallery bear witness to that. Scanning the lists of guests who attended his first exhibitions, Wattis grows sentimental. 'Did I really do all that?' he says.