Wherever it is, it rather looks as if all the staff are in the picture. The women on the front row of chairs, right hand side, could be teachers; young woman at the front dressed somewhat like a nurse/nanny; cook and housekeeper standing right hand end; even a possible housemaid towards the back in the middle. Boarding school?
Although just labelling it Folkestone, and the mixture of people may point more towards some sort of Summer School.
