Desmond and Chan are ex-hotel chefs and they started selling pao fan at a small market and food centre. They had two stalls there paying $8,000 per month including utilities to Andrew who operated the market and food centre under the style of "Lim Hong". Later, they were joined by Zack who started to sell Japanese ramen and Lawrence who sold fish soup. All four were selling food under an eating house licence held by Lim Hong market and food centre. They did their cooking in the kitchen at the back of the market and food centre and were allowed to use the tables and chairs in the market and food centre. The opening hours of Lim Hong market and food centre were 6.00 am to 10.00 pm. Chan would come to the market and food centre at 4.00 am to prepare his pao fan before the market and food centre opened for business at 6.00 am. He would wake Ah Hock up who was the manager of the market and food centre. Ah Hock would open the back door for him to come in and the back door would be closed but not locked. Chan would then open the back door for Desmond, Zack and Lawrence to enter. Some months later, Ah Hock handed the duplicate key to Chan so that he could open the back door to prepare his food. This was a private arrangement between Chan and Ah Hock as the latter was unwell. Andrew increased the monthly payments for all four stallholders and a disagreement arose between the parties. The four stallholders claimed that they had been refused entry by Andrew with the result that they could not do any business. They alleged that they were locked out because they had refused to pay the increased monthly payments.

Question: Based on the above scenario, analyze and discuss the concept of exclusive possession and whether Desmond, Chan, Zack and Lawrence were Andrew's tenants or were merely licensees.