Many thanks to all of you for your replies. It confirms my thoughts that it is a photo from the turn of the last century. They were not a wealthy family and are probably wearing their 'Sunday best' for the photo, so I would not expect the fashions to be up to date.
There was a policeman in the family, but he was brother in law to the mother (lady seated in the middle) In 1911 he is retired and living next door to the family.
I was wondering if it might be a 'Diamond Jubilee' (1897), or a 'turn of the century' photo? Did they do things like that in those days? Perhaps the policeman was on duty that day?
BTW we have a very nice watercolour portrait of a pup of that dog. He was a family favourite.