On the 13th, the Mirror faithfully publicised a new Labour poster lampooning the Tories. The Labour web-site points to David Cameron's liking for the X Factor twins, Jedward, as the motivation behind the 'shopped image.
Yet Cameron mentioned this quite a while ago. Does it take the Labour publicity machine that long to cut and paste Cameron & Osbourne's faces onto a stock Jedward pic?
Perhaps they were just stumped for inspiration before, lo and behold, a light bulb appeared above the head of one of the creative team. That, or a copy of the last issue of Private Eye, in the shops on the 10th (though available to subscribers earlier), dropped on their desk.
Now, I'm pretty sure Labour HQ keep an eye on, err, The Eye, so would have seen this. Or, perhaps, they don't bother with such scurrilous an organ, are not a party bankrupt of ideas as well as morals, and it's all just a strange coincidence.
You be the Simon Cowell (judge, geddit?).