I had an ongoing correspondence with WHSmith for a few months in which I questioned where their 1.2m restriction came from. According to a Department of Health age/height survey (available online), the height of an average 6-7 year old is 1.2m. Hardly hiding these mags from children.
In the end, they wouldn't put anything in writing and offered to speak to me on the phone instead.
Their head office isn't that far from me and I offered to go and meet with them to discuss my concerns but they didn't respond to that suggestion.
I don't shop in there or Tesco anymore. At least Sainsbury's took the complaints from customers seriously and covered them up, as did Morrisons.
It's hardly a big deal or very costly to buy some covers for the mags and move them up a few shelves.