Wikipedia says that the restaurant was in operation from 1955 to 1989, and that:
It was a landmark of Mong Kok at the time and served different segments of society on each of its five floors:
1/F was bakery with spittoon in the store that served grassroots
2/F was a Western restaurant
3/F was a Chinese tea housewith carpets (Chinese: 粵式茶樓 );
4/F was a Chinese wine house (Chinese: 酒樓 )with waiters serving customers with towels, and asked customers for tips;
5/F was a nightclub that served the upper class.