I’ve never smoked the stuff myself (latakia blech) but I found this excerpt from tobacco reviews.com...
“Standard Mixture Medium was originally the middle of three, the others called "Mild" and "Full". The term "mild" was abolished by the authorities in case we thought it meant its wasn't as bad for us, so this was rebranded as Standard Mixture "Mellow". When the Dunhill blends went to Orlik, Standard Mixture Medium was just labelled "Standard Mixture", and remained in production until the tragic loss of the Dunhill pipe tobaccos. Then the term "mellow" was also banned, in the latest round of enforced newspeak. Now, I've never smoked Standard Mixture Mild or Mellow, but I've had my share of Standard Mixture (formerly "medium"), and I'll eat my hat off the stuff in this tin, from the last of the Dunhill produced, isn't actually the milder offering rebranded in a bizarre case of newspeak tail-chasing. Such is life in these crazy days!”