The 'Boys' Life' issue August 2009 gives the card code 'TRUSTNOONE' for 5 free cards which are: Card 39: Gordon Klose, Card 43: Bletchley Park, Card 53: Alcatraz, Card 56: The Ghurkas, and Card 66: Blackberry. There is also a picture of Card 39C: The Clue Hunter With a Rank 3 Puzzle That says:
"AGENT IDENTIFIED: DAN CAHILL"
">>>CODED TRANSMISSION<<<"
I F N V T U O P U G J O E U I F D M V F
H M T
Answer:
H E M U S T N O T F I N D T H E C L U E - 'He must not find the clue.'
The code for Card 39C is 'ARROW4CLUE.'