Steve Holland forwarded a piece of information which reminded me to post this picture. I had always listed
Countdown as being the earliest copy of the advert for Crosse & Blackwell Baked Beans, but Steve has trumped me
Look and Learn 485, dated 1st May 1971 has the wonderful piece by Bellamy

Bellamy produced a lovely clear picture of knights in battle to illustrate the free pictures (on the rear of the wrappers)for the series
"Life as it was 600 years ago". I can't personally remember seeing the wrappers, but feel that C&B beans were too expensive for my family at that time!
I've added large scans on the
Advertising page of the website, as usual click on the Note

If you spot an earlier appearance I'd love to know