Midland Counties Ice Cream Advert from 1976 - Ice Lollies in Prison!

[FLYING SAUCER]

This is really bugging me lets see if you can crack this one please!

Pretty sure it was 1976 and Midland Counties had an advert with kids in Ice Lolly costumes with ball and chains round their ankles like they were in prison!

The main music went "Free a frantic ice cream from your Midland Counties cooler today!"

Any ideas please?