The late graffiti artist known as the "King of Kowloon" has finally won official recognition, with one of his works finding a permanent home in a public museum. The West Kowloon Cultural District Authority has bought a pair of wooden doors bearing the celebrated calligraphy of Tsang Tsou-choi, a legendary figure who died in 2007. Tsang left a legacy of graffiti on lamp posts, pillars and walls around the city that was derided - and often painted over - by officials, even though his work was praised by critics. Now the debate about his artistic worth seems to have been settled once and for all. Tsang's painted doors will be in the new M+ museum's collection when it opens its doors in 2017 at the West Kowloon Cultural District. The museum is still being built. The doors are among M+'s latest acquisitions since Swiss collector Uli Sigg's donation of HK$1.3 billion of contemporary Chinese art in June. The doors are large - each is 1.7 metres high and 2.2 metres wide - and covered with calligraphy written in ink and acrylic. Red Dog Studio commissioned Tsang to create the work in 2003. Studio founder Timon Wehrli said he did it to create an inspiring work that would help to promote Hong Kong art. The studio reportedly sold the work to the museum for a sum - not disclosed - that was below market price, even though an auction house was also said to be interested in buying it. The purchase won praise. David Clarke, fine arts professor at the University of Hong Kong, said M+'s focus on visual culture makes it an appropriate home for the work - although Tsang's art originally belonged to the street. "It is part of Hong Kong's popular culture," he said. "'Art' is only one frame you can put on his works." M+ executive director Lars Nittve has said: "The position of the 'King of Kowloon' as an iconic figure and source of inspiration to many younger Hong Kong artists can hardly be disputed." Born in Guangdong in 1921, Tsang arrived in Hong Kong when he was 16. He began displaying his graffiti around town when he was 35, claiming to be the "King of Kowloon". Over the years his work became an iconic signature of the streets of Hong Kong, inspiring many artists and designers. But government officials were not impressed. In 2003, the then chief curator of the Museum of Art, Christina Chu Kam-luen, said Tsang's "works are marginal art and controversial", and that the museum "can't collect any controversial art". Yet the Venice Biennale invited Tsang to exhibit his work that year. Last year a private exhibition showed about 300 of Tsang's works at Quarry Bay's Artistree, and a Tsang piece sold for HK$800,000 at auction. Meanwhile, the M+ museum has also acquired paintings by Hong Kong artist Chu Hing-wah. Other new additions donated to the collection include works that have been shown at previous M+ exhibitions, such as Michael Wolf's portraits from Cantonese opera and Chu's gigantic lantern, Harbour Viewing Tower, at the Bamboo Theatre exhibition. Yu Lik-wai's mixed media installation Fantomas , exhibited at May's Mobile M+ in Yau Ma Tei, has also been donated.