Puppets Andy, Teddy and Looby Loo first appeared on BBC TV on this day 11th July 1950. The episodes were repeated for more than 25 years until the film wore out. I remember my brother hiding behind the sofa when Looby Lou came on lol.
On the subject of I-Spy books, here is a display stand containing all the titles I remember from childhood. It includes the Membership Pack that I remember so well, that contained a badge and a codes booklet.