The idea is simple, vain, exciting. Tap the app, upload a picture of yourself, find your lookalike. Set up a meeting to see whether you have anything else in common. When Ella and Jem meet, the physical resemblance is uncanny, but their lives couldn't be more different. One is from a tiny island in a deprived Northern community - pretty much the back of beyond - where she has no job, no boyfriend, limited prospects. The other is a London...