This slide advertised 'Frosty Jack' ice cream- a Wellington brand which was sold from 1924 to 1967. Like many local companies it had a limited distribution- 'Frosty Jack' didn't even get to the South Island until the 1960s. However, this effort may have caused the company to lose money and they sold to a larger firm who then stopped making ice cream a few years later.
As early as the 1930s 'Frosty Jack' trays were being used in cinemas during the weekend matinee screenings which were popular with children. This slide asks the patrons to 'call the boy'- with carrying the ice-cream tray a popular first job for many schoolchildren.
Many of these cinemas would have been independent ones- Kerridge-Odeon ended up owning its own ice cream brand for its theatres.
Take a look at the boy on the slide- it looks as though the ice cream is giving him some brain freeze!
MAVtech has a 'Frosty Jack' ice cream tray in its collection and you can see it on Kete. Just search for 'Frosty Jack'.