There have been many unflattering suggestions made about the pictures of David Cameron’s strangely flawless-looking face on his £500,000 posters, not least from Star Trek devotees. Trekkies will yawn at the internet joke that the Tory leader’s Botox-happy appearance resembles the android Lieutenant Commander Data, but Tribune has a better idea. On the right is Constable Odo from Star Trek: Deep Space Nine, the naturally formless shape-shifter whose name means “nothing” and who never manages to look quite human. On the left…