Thanks for the link. Certainly sounds feasible. FWIW the credit card used for the purchase was a Mastercard. This would definitely go beyond what is described in the article though because (i) I'm pretty sure neither of us were shown any online adverts for football related children's books prior to going into the store (if we had they'd have stuck out like a sore thumb among all the unicorn, pony, fairy etc. children's books we normally see based on our purchase history), (ii) to target an individual's newsfeed the Mastercard data can't have been anonymised.