There were many small New Zealand soft drink companies trading in the mid-20th century and it seems that Foxton Fizz had some competition! 'Shamrock' branded soft drinks were made and sold by O'Connor's Cordials and online records suggest that this company was based in Levin.
The slide screened during cinema intermission and shows a group of happy children at a birthday party complete with novelty hats! The colour fading out on the slide would have emphasised the Shamrock logo and the contented faces.
Shamrock labels have been found dating from the 1950s. This slide comes from the 'Foxton' collection of slides. Rather brave of Shamrock to advertise in Foxton Fizz territory! Foxton's own fizz managed to survive the battle with international soft drink brands (just) but Shamrock didn't live up to it's lucky name and has long since disappeared.