You are all probably correct, the water level could have been very low, although tidal, because of an exceptionally warm and dry year the ages of my sons leads me to believe that this was 1976, the hottest driest summer I can remember.
I agree by modern standards these pictures are very poor, they were taken on a very basic camera, a Kodak brownie if my memory serves me well with roll film of the 127 type. the photo's were also printed in a matt format which made them very grainy, added to this they have been in the bottom of a cupboard for years.
I have recently decided that they should be preserved on my computer in case my Grandsons should be interested by them.There are quite a few pics so I may need to seek your help again
Many Thanks
Ron