The above cover franked with a 4 cent Queen Elizabeth the Second cent covering the first class local letter rate. I imagine that Christie's Hamper is much like the current hampers that people pay towards all year to have a 'hamper' full of food at Christmas. Perhaps they were giving a few away and a loyal listener wrote in hoping to win it.
Below are a couple of other covers complete with their contents sent in to Christie's C/O CJOB.
Saran Wrap had a contest on he station as well. This is demonstrated in the below 2 covers
Royal Upholsters had a contest as well:
The final cover I have addressed to CJOB is for the Robin Hood Rocking Chair contest.
CJOB was created by Jack Blick in 1945 to provide JOBs for people returning from serving in World War II.