My 2c,
Observations
The eyes and nose of the main man and woman are so similar I get the feeling they may be brother and sister rather than husband and wife. The dark-skinned lady shares the nose.
There seem to be several people that look almost exactly the same. Could there be twins in this group? There seems to be less variety in facial features than I would expect. The narrow bridge of the nose and the 'panda' eyes seems to be quite common among all of them.
The background vegetation looks like fir trees on left and right (one christmas style and one more rounded) and the rest looks like ivy.
There are six straight-backed chairs, perhaps dining room chairs. There are two metal chairs with unusual design and two fine wicker chairs.
Apart from the family and the two older men standing behind the lady with the white hat, they all seem to be of very similar age.
The surface they are on does not look like grass.
Thoughts
You need a special camera to take panoramic shots like this.
The presence of the wicker chairs suggests the tropics. The fir trees suggest not the tropics. Perhaps we are in the garden of a largeish home with a veranda. The wicker chairs would be from the veranda, the dining chairs from the dining room.
The two metal chairs are interesting. The seat seems to be made of bands of metal with gaps between them. I wonder if anyone who knows chairs would recognise them.
The dining chairs look like they have no arm rest, or at least a very sloping one. The legs are at an angle as if they are folding chairs but I don't think they fold. They are almost church pew chairs. Strange design.
I keep coming back to an army buddies reunion of some sort. This would explain the similar ages with the few exceptions.
It just feels colonial to me. The hem line rose much later in the colonies. I have a picture of me as a small child (1960s) in Africa and my mother's dress is still ankle length but very light material like we see here.
Do let us know what the H.G.Wells society say. That would be a lovely find.
Paul