1950s family beach photo

This is another photo in a series I've published on found-film which shows a group of friends or family members on the 'beach' at the Plymouth royal citadel. I find this photo interesting because there is a guy on the far left who seems to be looking at a slide using a daylight viewer - I wonder if he was looking at one of the slides which is now featured on this site?

Like many photos in this series, I had to apply quite a bit of correction to get colour back into the image - when viewed in the light this slide looked almost completely red.